How to glue painted tracks

The single-piece vinyl tracks can also be 'sewn together' with dark-colored thread that is virtually invisible. If 'sag' is needed, strategically-located straight pins inserted into the hull sides (with pre-drilled holes) are also easily concealed with most track designs. Alternatively, 'invisible thread' can be used to cinch the track to return rollers.

It's low-tech, but it works.

What kind of track are you talking about?  It does make a difference. 

One-piece vinyl, indi-link plastic or resin, indi-link metal, link and length plastic or resin, etc...

Each is handled differently.

I sometimes glue the top of my tank to the lower hull first and cant put the tracks on when they are attached. Is there anyway I can glue them while painting them before?

I never use metal or resin tracks. For kit tracks I use the same technique as above with liquid glue and careful adjustment of the rear track idler arm. I paint and weather the tracks after assembly and place them on the wheels just as below. After placement you can then add more weathering adjustment to the whole wheel and track assembly.

Even with so called "magic tracks" it isn't magic but after going through this procedure many times you'll eventually get the hang of it.

What kind of tracks,one piece or indie links? 

With one piece,you CAN use super glue,the newer Tamiya or Dragon one piece can use liquid glues like Tamiya or Testors,but BEFORE painting is best.

From the way your question sounds,I don't think you are talking plastic indies,but that's a whole other discussion,those are assembled with liquid cement also,usually before painting.Here's who I handle plastic indies.

Unless the tracks are resin and you are very good, never use super glue, or CA glue for plastic models.  As Joe said, paint the tracks later.  Its tricky sometimes, I just finihed two Dragon kits last month with link to link tracks. I did them both by cutting off the sprues first, they were from the nineties, then assembling them in sections then painting them.  That is the short story. It's longer in reality.  Tanks used to be much easier years ago.  Oh well.