To make sure you have properly connected to the right ad account, you can go to the settings page of the Shoelace app. In the section "Connect to ad account", you should be able to see the account that is connect to your Shoelace services.
If this is not the account you'd like to connect to, you can hit the "change" link on the right to choose another ad account you'd like to use.
Don't see the ad account you'd like to use? Sometimes our merchants run into this because they haven't claimed their ad account yet. If this is the case for you, you can follow the instructions here to claim it: http://help.shoelace.com/account/how-to-claim-your-facebook-ad-account-in-business-manager