Unless something has changed recently, you cannot change the surname of a profile if you are not a profile manager. Maybe you have to be on the trusted list.
Anyway, spelling was not exact in previous centuries. If you have a different spelling, it is a good idea to add it to the other last names. It is not necessary to change it unless all of the sources have the same spelling.
If you have proof of a discrepancy in the LNAB you should get in touch with the profile manager and discuss changing it.