Make people select from drop-down and not allow copy and paste

[StacyJ01]

Hi, I have exhausted looking for a solution on YouTube and other google searches and in desperate need of help.
I have a file where I created a data validation drop-down list in column A in my spreadsheet. I want my users to HAVE to select from the drop-down list and NOT be able to override it with a new supplier name by doing a copy and paste or CTL-C and CTL-V. I have tried a couple of options, but nothing seems to work the way I want it to. I have locked, unlocked, protected & unprotected, but nothing seems to work. I am open to having a macro in the file, but I am a novice and not really sure how to write one. I am running Win 10, if that matters at all.
Any help is greatly appreciated!

 

[6StringJazzer]

Is this one cell, or all the cells in column A?

 

[StacyJ01]

I would copy my drop-down list selection to 75 to 100 cells in column A.

 

[6StringJazzer]

One option is to to use a macro so that when a user selects a cell in column A, instead of having the user type into the cell, a UserForm comes up for them to type into. The code in the UserForm copies the data into the cell. Here is a demo. Click on any cell in column A to see how it works.

StacyJ01=Protected data entry.xlsm

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