@Emme Developer why not just use #SignKeyFile and #SignKeyPassword once in your Main Activity. Doing it the way that you suggest is long winded. You still leave you main key file name in private key sign, but you use #SignKeyFile and #SignKeyPassword in the Main Activity to bypass the default keystone with the one you actually want to use in that particular project. I place mine in the project attribution #Region of the Main Activity, once set I don't see it again
#SignKeyFile: c:\folder\folder\b4a\mykeystorefile.keystore
#SignKeyPassword: ilovelife
It's as simple as that...