Rolling back an APK install to a previous version

Question

I have been using APKMirror update which helps me see if any app updates are available. I had it connected to only check Google Play which worked great for a long time

My problem is that there was an update flagged for Samsung Internet and when I downloaded it, I realised that it had downloaded from Aptoide and it had installed a foreign version of the app. (I think it may be chinese but not 100% sure)

I uninstalled the app, and then downloaded the current version from Galaxy Store, which was a slightly older version that Aptoid provided

However, all it done was reinstall the Aptoid version. I tried using Google play and had the same issue.

I then went to APK Mirror and downloaded the version that is available from Google play and Galaxy store, so that I could install manually.

I get an error telling me App not installed as package appears to be invalid

But the reason for this appears to be found when I try and install using APK Mirror Installer

I get an error App Installation Failed, The new package has an older version code than the currently installed package

I have uninstalled the app but there appears to still be remnants of the app on the phone which is making it difficult to revert.

Are there any recommended steps to take to rectify this issue?