I recommend fully logging out of your personal Gmail account and then logging back into your FCS account. 

To log out:

1) Open your Gmail and locate your profile picture in the top right hand corner of the screen

2) Click on the image to open a dropdown menu

3) Select "Manage Accounts"

4) This will open a new page and you should see your FCS and personal email addresses listed. At the bottom, click "Manage Accounts on this device"

5) This will open a new window and you will see your accounts again. Find your personal account, scroll to the right and click the 3 dots. Then select "Remove this account:

Your personal account will then be removed. Let me know if you have any questions.