If you are listening to a Dolby Digital or DTS source which has been selected or flagged by the DVD player/ games console/ sat box, the amp will switch to DD/DTS. It is then up to you in most cases to select whether you want this to be EX/ES with the amp remote.
Pro-Logic will activate when the same units send a stereo signal to the amp. Again it is up to you to select the mode you want. The names were decided by Dolby but basically break down to the following;
Movie- best used on material encoded for Dolby surround or better (the Simpsons is a prime example)
Music- Best applied to material generally encoded in pure stereo
Game- Provides artificially high rear speaker levels.