The delay in updates is somehow normal. The latest version will appear shortly when it will be posted. No app on the Internet (or AVG) will give you instant updates when developers release it. Just wait a day or two and the update will appear in Software Informer.
Unfortunately, if the Power2Go doesn't have an option to go back to a previous version, then it's impossible to do it and that version you need has to be downloaded manually again.
Software Informer won't update the apps automatically. You will have to press the Update button in order to start it, therefore you are safe with your apps.