In worksheet 1, cell e2 I have a drop down list of 5 items. The end user of the worksheet will select one of these, which will be periodically updated. I want the end users selection to be copied to other worksheets (over 80 in total) to cell e1. Using
Formula: copy to clipboard 
='worksheet1'!E2
the current selection is properly copied to all my other sheets.

To make sure te end user can't delete or edit the formula and to keep all calculations are correct, I then protect cell e2 on my secondary sheets. As long as protection is off, any changes to sheet1 e2 are copied. Once I turn on protection, the secondary sheets no longer update if worksheet1 e2 is changed. Even after I turn off protection, I have to select cell e2 and hit enter to get the data to change.

My question is How can I keep the end user from accidentlly (or purposely) deleting the formula in e2 on my secondary sheets, yet let it change when the end user changes worksheet 1 e2?

There are formulas on the secondary sheets that rely on this data.

Any and all help is appreciated.