Drywall Cracking in Corners
Forget the colors of the lids. They vary from area to area, here the colors are different than the previous posters are stating.
You're cracking could be many different things, without a picture it's hard to guess. The house could be moving, the drywall could be loose and not attached properly, you could have left too large of voids, you could have used the wrong drywall compound material or used it incorrectly.
Keep your drywall joints tight.
Use Paper Tape applied with JOINT COMPOUND (here the pail is YELLOW)
Coat with either All Purpose or Finishing mud, it doesn't matter which.