Do changed prices affect bookings that have already made?

Our holiday house offers a maximum capacity of 6 persons. I want to change the standard price to 4 persons, which means guests will pay more for 5 and 6 guests and less with 3, 2 or 1 guest. Does this change affect the bookings that are already made or will it apply only for future reservations?
By doing this I hope guests will not receive a notification that the prices have changed. I'm okay with the bookings that have already made with the prices of that moment. Don't want to bother these clients afterwards. I only want to change it for future reservervations. Can someone confirm this please?