Welcome to Yamaha Synth! Thanks for the question.

My question is how do I remove the E sign without switching off. I know it is telling me that I have altered a performance and have not saved it but I expected "quick reset" to remove the E. Perhaps it doesn't matter and I just ignore the E unless I actually intend to modify a performance?

The "E", as you correctly state, is just an indication the data occupying the Edit Buffer differs from the Performance as it was originally STORED in this location. There are several options to remove it.

_ You can, of course, press [STORE] - you would do so if you like the changes you have made and wish to update the current Performance or direct the newly edited data to another Performance location.

_ You can recall the current Performance by pressing the (lit) Program button that allows you to directly select Performances.

_ You can press the [EDIT] button (flashes) and the "E" will change to a "C" for Compare... You would use this to compare the current condition with the original data for this Performance. This is used to A/B what you've done with the original programming to see if you like the changes you have made. Please note: while in Compare mode no further changes can be made. Press [EDIT] again (light goes steady) to exit the Compare mode.

Mainly, the "E" is just an indicator and can be ignored. You have a good grasp on the reason it is there_ just to alert you to the fact that the current condition differs from what is STORED in this location. What you do from there is up to you.

If you move to a new Program, the "E" naturally disappears as you will populate the Edit Buffer with the new Performance's data.
Enjoy your new CP4 Stage!

Hope that helps.