Sometimes two or more people work on Future Planning at the same time.
If you're actively working on a week, it will be locked to all other users. You can select the lock icon on the Quick Access Toolbar to lock a booking.
After you've finished and saved your changes, it will be unlocked for everyone, until someone starts actively working on it again.
If you start working on the planner and leave it open without saving your work, someone else can unlock the planner and work on it, erasing any changes you've made. We recommend you save your work often.