Is it possible to back up my present schedule before editing it just in case I am not satisfied with a new schedule so,that I can just return to my previous settings without having to reprogram everything from the beginning?
I will commonly write 2 or 3 schedules in advance. You choose the one that you want to use. In your case, you can write an identical schedule, make the tweaks and adjustments that you would like and just disable the original.
You can always disable the new program and re-enable the original. As long as you don’t delete a program, it will always be at your fingertips.