inoperative Dock option

My first thought is that this is a Microsoft problem, but, because I am on a Mac, I ask here, too.

I have two Microsoft applications set to start up on log in.  These are Excel and Word.  When the computer starts in the morning, Word and Excel automatically start up.

Recently I installed Word v. 16.16.11.  In contrast to every preceding version of Word, the Microsoft Updater installed the new v. 16.16.11 as a new application in the Applications folder without deleting the old v. 16.16.10.   I now have both versions of 16.16 in the Applications folder.

In the Dock I have set v. 16.16.11 to start on log in.  But I cannot get v. 16.16.10 not start on log in.  Every time I go into the Dock, I click “Open at Login,” and nothing happens. Now both versions of Word start at log in.

I have asked in the Microsoft support forum about this problem.  So far no one has any answer.

On the off-chance that this is an Apple problem, I ask here.  Is there any way to click off the “Open at Login” option?