Brad Saucier

The only way is to advance to the next stage setting with a pedal, which in turn can change arpeggios.

Select the upper tone you want before enabling split mode.  If you've already enabled split and want to change upper tones, undo split mode. 
 
Note: "Pop" is not the upper tone.  That is the name of the current Rhythm selected, as indicated by the letter R next to the Rhythm number.  

Waveform (wave) level access is only available within hex layer tone editing.  Hex layer tones must be saved in the hex layer user tone category. 

Double check everything.  You missed a step somewhere, and it's difficult to say where.  Maybe a video would help us spot it.  For what it's worth, many factory synth stage settings have cutoff assigned to slider 1 already.  Video tutorial below with a clickable index in the description.  
 
 

Casio SP-20 and SP-3 are available.  They're compatible with all Casio models.  

I will repeat this because it can't be said enough.  An interrupted firmware update to the XW series can be restarted in most cases.  Up until the point someone presses the OFF button on the synth, nothing is damaged.  Simply restart the updater app.  It will continue to update from the point it was interrupted.  

https://www.casiomusicforums.com/index.php?/topic/14215-useful-links-to-mzx-series-manuals-mzx-software-and-expansion-files-community-shared-files/

Unfortunately the arpeggiator is only available for upper 1 and upper 2 parts.  It's not available for a lower split tone.  

Press function, go to "other" and press enter.  Go to Auto Resume (AtResume), and turn it on.  It will remember reverb level and many other settings after a power cycle.  

Press the function button and go to "auto resume", turn that on.  This remembers most settings after powering off.  
 
Note: We need to rename this topic.  It should reflect the question being asked rather than your name.  You can do that by editing your original post, or I can do it for you.  

They are shoulder strap locks.  My shoulder strap came in the other day coincidentally, so I could take this photo for you.  
 

 
 

Whenever you run into something like that in a keyboard product, it usually means the default value (labeled "tone" here) is in the middle of the range of user selectable levels.  This particular setting has 4 user levels.  So 1 and 2 would be less than "tone".   3 and 4 are more than "tone".  Leave it set to "tone" if you are happy with that sound.  

That is not possible.  The CTX does not have 5 pin MIDI ports for connecting directly to another keyboard and it is a different type of instrument than the XW, not designed to change registrations remotely.  USB MIDI on the CTX is mainly intended to be used as a sound generator for software sequencers and MIDI file players, where bank and program change data is used to select tones.  The USB MIDI input on the CTX has an independent sound generator not tied to the "live" sounds you hear whenever you're playing registrations on the keyboard.   

Half damper pedals are not compatible.  That model pedal is a half damper pedal.  You'll see a TRS plug on the cable for the pedal as an indicator of this.  You'll need a standard on/off switch type pedal with a TS plug on the cable.  

The action in the PX-770 is called "Tri-Sensor II Scaled Hammer Action".  You can find the same physical action in portable models like PX-360, PX-560 and PX-5S.  I personally practice on my PX-5S daily and really enjoy it. 
 
I'll add this note in case it's of interest. Casio recently released a premium portable action with resin/wood keys which is getting great reviews.  Entry level on that action is with the PX-S5000.  I can't speak from experience with them, but it's worth a look from everything I'm reading.  

I don't have experience with the app.  I can only suggest trying the solution.  It may work for Android as well.  

Overall knob function is determined by the "knob set" selected in the CTRL KNOB menu.   This does not change with tones, however it can change with registrations, depending on how registrations are being used.  
 
Unfortunately whenever the selected knob set is "DSP parameter", there is no chart showing which specific DSP parameters are adjusted.  

Turn on "auto resume".  This saves most settings.  Details about auto resume starts on page 4 of the PX-870 full user guide.  The full user guide can be found here in PDF format.

To control 4 parts (tones) on the MZX, you will need to select or create a 4 active zones stage setting on the PX-5S.  You'll need to make sure MIDI out on the PX-5S is set to "key", in system settings under MIDI.   
 
On the MZX, you'll need to set MIDI in port to A, if you're looking to control upper and lower tones.  

To clarify my previous post, "touch button sensitivity" and "touch response" are two different things. 
 
"Touch response" controls sensitivity of the piano keys. 
 
"Touch button sensitivity" adjusts sensitivity of the user interface buttons on the top panel of the instrument. 
 
To recap, look for "touch button sensitivity".  Try reducing the sensitivity of this setting to reduce sensitivity of the buttons on the top panel. 
 
Note: The keys don't need air in this situation. That is not where the problem would be.  
 
Page EN-45 of the user manual for reference....
 

Casio Music Space and Chordana apps have MIDI songs built in.  This is like playing any other MIDI file from other sources, like PC software using the piano as a sound source. 
 
The manuals are where I get all of my information whenever I answer questions here.

Oh yes, you can do that.  While it's playing just press the plus or minus button to skip to the next file.  

The same rules still apply to hex layer tones in the song sequencer as stage settings do.  The PX-5S is a 16 part multi-timbral instrument, and only parts 1 and 2 (zones 1 and 2) can handle hex layer tones.  You need to edit the song, go to the song mixer and channel the output channel to 1 or 2 for each track you want using a hex layer tone. 
 
Another note, if you happen to create a user drum tone in the future, user drums will only work on channel 1.  

Press system setting, sound generator, audio volume.  This was added in a firmware update.  If it's missing in the menu, you'll need to update.  

You should see a white sticker on the bottom panel with a barcode.  That number is it.