How to install "old" IOS apps?

I'm running iTunes 12.5.6.3 in order to be able to manage my IOS apps. Unfortunately I've upgraded an IOS app to a newer version and that version is crap compared to the old one. I have the old ipa file and I've copied it back to the Mobile Applications folder in iTunes, but it's not showing up in "Library" in iTunes, and so I' cannot install it on my iPhone (I've deleted the new version, of course). Tried to rename the ipa file. Same result.

Is it at all possible to "re-install" an old version of an IOS app and how do you do it?