Optimized versions autoplay?

I play my media on several different devices and am now optimizing my videos for each device. I am using the “custom” presets. Like The “Xbox One” preset. But, when I use a device just by selecting the movie does plex automatically select the correct version? When i check the quality, it just shows me the bitrate its playing at. not which version its playing.

Or do I have to manually select what version I want to play on each device every time i want to play something?

Sorry if this has been answered before but i couldnt find any other posts

Lets say the original is a 1080p 8Mbps file and you create an optimized version that is 720p 4Mbps.
Now if in the plex client you are using you select quality setting of a bitrate lower than 8Mbps (the original bitrate) the optimized version should play.