How can I see only posts for a specific account that I am working on?

You can use the filter feature of the calendar.

Click the icon with three lines on the top left corner of the calendar.
Click on Filter > Filter By > Social > Facebook / Instagram then select the account/s you want to see on the calendar.

This can also be done through the 'Campaign' feature that is already included in your subscription.

Here's a quick video tutorial on how you can use it: 

Filter Calendar