MX16.1 can't set repo via MX Repo Manager

[mxminty1]

I am having issues with MX repos and updates. Started a few weeks back when update for Firefox 69 threw an error about incorrect file size.
Check of the forum indicated that MX15/16 repository had to be changed. Which I did, but running apt-get update got stuck trying to connect to mirror.freedif.org. Turns out that this the last entry in the MX repos and being in Vietnam (where I am not) would make for a slow connection.
So I try to select another repo, use the "select fastest" option, but no matter what I do after hitting apply the option returns back to the last entry.

Good news is that for some reason, today's update ran from la.mxrepo.com. Not the fastest but I got the Firefox update through. Checking inxi -r confirms that la.mxrepo is being used, but again in MX Repo Manager the MX repo tab is stuck on Vietnam mirror and any changes will not stick.

Should I just edit the source.list files directly to specify the repo I want? Thing is, when earlier I went through those files one by one (before I learned about inxi -r) I saw no mention of mirror.freedif.org and was puzzled as to why the update was trying to use that repo.

Any suggestions would be appreciated as I don't want to get stack again with a system that can't complete an update. Thanks.

[Adrian]

Here are the original MX-16 sources
https://github.com/MX-Linux/MX-16_sources

Compare what you have with these sources.