Ok so ive been using ableton for over a year pretty constantly, though its come to the stage now where i need to change the BPM mid song, though i cant find how i do so without editing the entire grid and messing up the rest of the tracks in the process.
Basically, how do i isolate a few bars and change the BPM without affecting the rest of the mix in any way?

you wanna buy a bus ticket mate?
I dont think this can be done in Ableton Live, its a been a while since i used it though, check the manual.