You should just have combined that with your other "modifying" questions. I'm sure you do not want to add the same manager to all of those users?
It is usually better to give us the bigger picture in a single question, and let us decide whether it makes sense to split the question.

You have a point,. It's a good point, I believed that splitting the question would be easier and less confusing. It sounds like I'm asking for a big bag.. and that might stop anyone assisting; whereas a smaller request might get answers.

I think I have a clue to this one.
https://4sysops.com/archives/configuring-ad-users-and-managers-with-powershell/

I need to script it.. if you have any ideas, let me know.

As you can see from the link, setting the Manager attribue for an user is easy. It is the logic which requires effort for bulk changes.

You already fooled me in https://www.experts-exchange.com/questions/29065282/Powershell-Batch-Update-AD-User-Object-Member-Of-Tab.html by not providing any details, leading to "answering" the question yourself (using semi-optimal code).
I will refrain from providing suggestions as long as you do not show the (desired or real) input file. Or confirm whether it is indeed just a text file containing user names only, and you want to add the same manager (and in regard of https://www.experts-exchange.com/questions/29065280/Powershell-Batch-Update-AD-User-Object-Organization-Tab-Job-Title.html the same job title).

Thanks. Apologies for any perceived misunderstandings and believe me, it wasn't intentional.

I do have a text file with usernames. I can't attach the real one; confidentiality aside, the whole story is that there are 85+ individuals in various OUs that I need to move into one OU. In this process, I need to update their "manager" and "job title." Once I have these users in the OU, I need to apply two or three GPOs to them.

That's the whole background.

I truly felt that if I broke this request into segments, it would be easier for anyone who reviewed the issue. I found one method parts thereof, however there are times that I need to only perform one aspect and not all of the segments, i.e. just update a number of user's manager etc. This is where the split was most beneficial to me.

Again. I apologize for any misunderstandings. I also sincerely thank you for assisting me in the past, with advice and actual code. Your work and understanding is by far top notch.

Good answer! Thanks. Explanation helped.