If your main computer, which synchronizes with portals is the reception one and you need to change the prices on the portals from your laptop or an office computer, you can enable synchronization with portals on those secondary computers. but you must select the option Only for price updates in connection tabs. Please have a look how if should look like for all the portals:
Booking.com:



Hostelworld:




Hostelbookers:




Hostelclub:



Expedia:



Please note that keeping this checkboxes checked is a necessary condition for running synchronization on two computers simultaneously.