1. Why does the active sheet have to be unprotected?
dsCopyFinder reads formulas on the active sheet and may need to color some cells on that sheet. It is not possible to do this if the active sheet is protected.
If either the workbook or worksheet is password protected, you will be prompted for the password.
3. I pressed the "undo copy coloring" button but some cells remained highlighted. Why did this happen?
dsCopyFinder remembers the positions of copied formulas and then uses this information during the undo process. If in the interim you have inserted or deleted cells then the positions of some formulas might have changed. This can interfere with the removal of cell highlighting because dsCopyFinder has no way of knowing that cell positions have changed.
For reasons of efficiency dsCopyFinder does not look at any worksheet's initial coloring scheme. This allows dsCopyFinder to run as quickly as possible but it means that original colors cannot be reinstated.