What if only some seats on a board are open to applications?
Navigate to the board and click Manage. Now click Edit Board and under Application Settings set the Accepting Applications drop down to Per seat. Scroll down and Save.
Now you can use Edit Seat in the Actions drop down menu. You will see a check box to Exempt seat from Applications (see image below). Check that box and hit Submit, then repeat for each additional seat that should not allow applications.
Exempt from applications