Optional: If one or more of your ad accounts is owned by a Business Manager account, click your profile image or Business Manager logo in the upper-right corner of Campaign Manager to ensure you’re viewing the correct profile or Business Manager account.  

• When you view your list of ad accounts to switch accounts, only ad accounts owned by the same Business Manager will display. 
• Ad accounts not owned by a Business Manager can be viewed when you select your profile.

Click the ad account name in the upper-left corner of the page and select the correct account name from the dropdown.