Unfortunately, changing associated Google Accounts is not easy.
However you can invite other Google Accounts, including another that you use - to allow multiple users to access a single A2X account.
From the settings section of your account, Users can be invited or removed, see the screenshot below. Go to Settings, and then choose Users.
Below is a screenshot of the User management interface
Addendum: If you are the Admin, you can also switch Admin to the account with the blue button, as above.