Based on the best practice guidelines you should make it clear to any users of the Financial Model (including yourself) where you can and can’t make changes to inputs. So you may need to protect certain cells from being overwritten (typically the formulas).
This is easy to do in Excel but you need to change the way you ask the question to better understand it. Most people will say
I need to protect these cells
but the more correct statement (given how Excel works with this) is to say
I need to UNPROTECT these cells (the ones that won’t be protected)
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