I appreciate you taking the time to respond with these sound suggestions. The disappearing email signatures were one of many problems I've had with this Air. Since it's arrival a few days before Christmas, I haven't been able to access my iCloud documents on my computer. Several senior specialists tried to help me with that, to no avail. And it was periodically crashing, forcing me to recreate the documents I was composing.
I have the M1 chip, so safe mode was not an option. I decided to call for help. At the direction of Apple senior specialists, I have erased the hard drive and reinstalled Big Sur five times within the last 24 hours. After the initial erasure, I used Migration Assistant to migrate the data from my MacBook Pro (the third migration attempt). This time, it announced that it was unable to create a user account. Consequently, we tried more erasures and re-installations.
We finally raised the white flag when it absolutely refused to create a user account--even a test account. That essentially rendered this pitiful piece of equipment useless. (Imagine my delight, after having paid my initial Apple invoice in full--prior to the due date!)
Luckily, I had purchased it online. That gave me 30 days to return it, rather than 14. (Whoo-hoo!) I happily dropped it off at FedEx moments ago. My daughter's new Air with Intel processor has performed flawlessly, as we have come to expect from our Macs. I'm a bit gun-shy now. I was excited about the Air, but I'm fleeing back to the MacBook Pro.
Again, thanks so much for your offer of help.