Even though you are connected to multiple accounts, you have to be logged into a specific account to see shipments to pack and to pack shipments.
You can see on the dashboard which account you are currently logged into
To switch account follow the steps
Step 1: Click the scanner navigation in the lower right corner
Step 2: Click the account name in the top row
Step 3: Click the account name you wish to login to
You are now logged into a different account