That is very upsetting! You said that it also fails to remember settings during a power failure too? That is a fairly large safety issue, I am guessing it defaults to a original temperature? Jabberwocky Dragons is your unit doing a similar thing? I would send an email ASAP if it fails to hold settings and is problematic setting them that sounds like a bug in firmware or chip set.

Personally I'd return it, that is too much for me to trust it again especially with Jabberwocky Dragons mentioning similar problems, would a new unit fail as well?