It's reasonable to assume that once a feature, like a command button, appears on a screen, somebody will get accustomed to using it. When the software product evolves and that button needs to move, some consideration might be given to those users who will be disrupted.
Since many buttons don't perform an action but only invoke a next menu, maybe the old button could be dealt with there. This looks like one of those cases.
Tap Sketch button, get menu. One menu option: "Hide Sketch button and show Setup".
Tap Setup button (in that spot), get menu. One menu option: "Hide Setup button and show Sketch ".
That way its reversible.