Lock some cells in all sheets
I want to lock some cells in all the sheets at once. Please guide. Thanks
Any time you want to do something to all sheets at once, or any chosen subset, just select the sheets (using their tabs) and then perform the "something" on one of them. It will occur in all the same cells in all the selected sheet.
Protecting the cells is no different. It's just a format. You could, by the way enter data, or formulas, perform a paste, move columns or rows, create filters... almost anything you can think of doing. With protection, be sure to do the whole process including going to the ribbon for the last step.
Your only worry is that you select a page that should NOT be included in the change. But there are all sorts of mistakes like that to make in every spreadsheet, so likely you're on top of that kind of thing.