If you have an expanded track all your transitions top and bottom line up now in just one I want to edit the time transition in just track a without effecting b
Transitions are the interaction of two overlapping events. Since the overlap is the area that is common between the two, you can't have the overlap duration of one event be different than the other.
What you can do is put the events on separate tracks and use fades. Drop the transition you want on the fades of both events, then set the timing on the two independently. However, since most transitions depend on the interaction between the two events where they overlap this method may not work well for many of them and often won't give you the result you're looking for.
The other thing to do, Rory, is to do your thing and if you WANT differential timings of T1 and T2 add a "Transition Progress Envelop" to the End of T1 Event and the beginning of T2 Event. This ways you can sustain/reverse/hold and just do what you . . . . wish!
It offsets the Snap. The Snap is the point at which Events will be "felt" to snap to each other. You will also see the vertical Snapping Coloured line indicating as much. So, if you wanted to Snap two events, but one inside the other, you would offset the snap. I can't remember I've never done it!
Insert / Envelope / Transition progress only works when you've applied a transition. If you only have a plain crossfade then it's not available. Even with a transition progress envelope, the timing of the transition on the two clips will still be identical.
If it really is just a crossfade that you're after and you want different fade durations for clips A and B, using two separate tracks is the way to go.
FWIW:
Sometimes there's a transition I want to use during the fade to black. But because I don't have another event butted up against the event, the transition doesn't want to function.
So I keep a "blank" (you know, just the transparent background) .png file lying around. I butt that up against the event in question. Slap whatever transition on there, and it works.
Minutes ago, I was helping a guy get through the same situation in FCP. Now I know it works there, too, and FCP comes with a lot of transitions that won't work on stand-alone clips.