lou0417 correct me if im wrong in understanding with your concern,..
you have existing Gcash Account, and you wanted to update your account? from this you may opt to go to the nearest globe store for updating information bring valid IDs with you and have ask for help from the staff of globe store.
Actually I don't have yet an acct n globe
first you need to have a globe prepaid or globe postpaid sim, you may activate your gcash via *143# just follow the instruction
Right at your fingertips..lou0417
on your mobile phone, dial *143# choose GCASH then REGISTER
REG <4-digit PIN/mother's maiden name/first name/last name/address> and send to 2882
also check on this Get Started | Mobile Money | Services | GCash - Globe