How do you deal with a client in which you have to frequently explain the changes they requested back to them?

Not sure I follow you, I am self employed and if changes are requested the request is written up together with any implications, timescales and costs and possible alternatives dependent on what they want to achieve (also costed). There is no ambiguity. These are signed off. If you are in an organisation this shit should not really be your responsibility.

Ensure that they're paying you to do so. Then, evaluate if you like what you're being paid to do.
If you're not getting paid, find a strong diplomatic excuse not to do it.

@helloworld it is someone's. Maybe his.

@helloworld Definitely one of my clients. Good guy, I completed an update to an app for him, but had a significant (multiple month) delay before he could test and verify all was working. It seems he's forgotten all but broad strokes of projects.

@OmgItBurns but the written proposal and spec should remind him, just resend those.

@helloworld You are absolutely right. I'm also going to give him a quick demo of the changes, he tends to pick things up better that way.