Do the following to change to a different account:
1. Click "FILE" in the top left menu bar.
2. Select "Manage Account" in the dropdown box.
3. Click the radio button next to Silver or Gold accounts respectively.
4. When the circle is filled next to the account you would like to activate, click the "Activate" button at the bottom.
Note that some achievements in Beeline require that you complete them on a specified account. Be sure these requirements are met or the achievements will not be completed.