Hey Guys,
i have a problem and can`t figure this out by myself (again). I´m working on a project , and every time i`m recording a new track, the notes of all the existing midi tracks get recorded into the new track aswell. Could not figure out how to stop this yet.

This may be a combination of softsynths with "Enable MIDI Output" selected for the synth which can send MIDI and MIDI tracks with input set to Omni.
 
It is a good idea to only "Enable MIDI Output" when needed. The option defaults to on where available.
 
It is also a good idea to specify the input source for a MIDI track instead of Omni.

Once again you are my life-saver, scook. If you`ll ever visit (South) Germany , i`ll buy you a good franconian beer :-)