If it's a Mac you are unfortunately fucked (idk abt pcs). You can't change the name of the admin without potentially breaking the os and losing your data. You can maybe back everything up onto a separate hard drive & then do the change & reupload everything (& make apple fix the OS if it breaks - if you can afford that...). Or you can make a second admin account on the computer & give it your name
If you’ve been changing it locally in settings and it keeps reverting back, this is probably the reason (it pulls your Microsoft account into online and updates), so lmk if changing your Microsoft account info changes anything. If you can’t change it bc it’s a school or work account where you don’t have admin privileges, you might have to file a ticket w/ IT but it should be pretty easy / fast.