Updated Plugin, Can’t Change Field Keys

I tried updating from 3.0.3 to 4.1.17, then all of my admin fields disappeared from all products. I recreated the admin fields and they show again, however the field names/keys are now cryptic in the new version. I tried editing the new name to match my previous name but it won’t save. It always reverts back to its cryptic value. Example Field: Label: Fixed Price. Previous field/key name: fixed_price (wccaf_fixed_price). New field/key name: wccaf_sjkhdskjhd. How do I change this cryptic name/key to match with my v3 name/key so my old fields will show properly? In the meantime, I had to revert to v3.