Schedules change. A class gets added at semester, a period is dropped, the calendar shifts. Every structural setting can be changed after the year is under way — but they don't all behave the same, so here's what to expect.
Safe to change any time
Orientation, title, day title, and the title period are display settings. They redraw the grid and touch nothing else. Flip them freely — see Planbook advanced options.
Planbook name is just a label.
Days of the week hides or shows a column. Plans on a hidden day aren't deleted; add the day back and they return.
Change with a little care
Adding periods is safe — new periods go on the end, empty. If the new class belongs mid-morning, add it and then reorder.
Reducing periods removes them from the bottom up, and it's the count that decides, not which period you had in mind. Plans in hidden periods aren't erased and come back if you raise the count again, but the safe habit is: reorder the unwanted period to the bottom first, then reduce.
Start and end dates control which weeks exist. Moving the end date later adds weeks. Pulling the start date forward or the end date back means weeks outside the new range can no longer be reached — the plans in them still exist, so widening the dates again brings them back into view.
Think before changing
Rotation re-labels the cycle from that point on. It does not shuffle plans you've already written, so a mid-year switch can leave earlier weeks labeled on the old cycle. If you're correcting a rotation you set up wrong at the start of the year, do it as early as you can.
When a copy is the better answer
If the change is large — a completely different schedule at semester — consider copying the planbook and setting the new one up the way the second half of the year actually runs. You keep the first semester intact and readable rather than reshaping it into something that no longer matches what you taught.
Whatever you change, plans are keyed to a date and a period. Layout settings decide what's drawn, not what exists — which is why most of these are reversible.