Good tip!
I back up frequently then restore the old version if I don't like an update. But this week when I didn't like the update to the X-plore file manager Google Play Store would not allow me to re-install an older version. So I'm stuck with the Ice Cream Sandwich updated version that has type font that is too small
Try deleting data on that new APP you want to uninstall 1st, then uninstall the APP & reboot it your device to delete the cache.
Then try installing the older version.
That is if you have it backed up somewhere & not trying to get it from the Play Store
But if you don't have the older version of the APP, trying searching for the older versions, sometimes the APP developer
will have the older versions available on their site or you can try to email them.
Hope that may help