DSP chains apply to track 1, but not 2. How do I apply different ones?
Move the cursor into Track 2, then the DSP chain displayed below will reflect the contents of Track 2.
You can move the cursor with the Tab key, or by double-clicking in Track 2 itself, etc.
If that’s not what you meant, then I’d be happy to give more suggestions if you can provide a bit more detail. 
Or if you want a DSP Chain to work on more than a single track you will have to route all tracks you want to effect to a Send track using the Send Device in Routing DSPs, then apply the DSP Chain in the Send track.