Hi,
You can't change the callsign in your account, it's the KEY of the database !!!
What you need to do is create a new, attached account for the new callsign.
Log into your existing account and go to the 'My Accounts' page,
https://www.eqsl.cc/qslcard/MyAccounts.cfm .
At the bottom of the page you will see a section called: 'Register a New Attached Account'.
Change the callsign to be your new one, put in the start date of when you received the new callsign, and press the 'Create New' button.
The new account will be attached to your old account, so they will share the same membership level, and also the credits from both accounts will be combined for the eAwards program.
73, Guy F6DKQ