One Instance of Dragon Player?

Hi. Is there any way to make Dragon Player so there is just one running instance of it at a time? Like if i have something playing and i click on something else to play have it so that the instance currently running changes to the new file instead of opening a new window?

Not within Dragon Player itself, since it does not even offer a proper configuration dialogue (just to be fair: DPs approach is to be a most simple player). I recommend using a different player, for example the fantastic →SMPlayer, which does offer to run only one instance at a time. In case you prefer a Xine-player, use Kaffeine (which does run in one instance only).