All corners cracking

That would do it, try latex caulking, apply a small amount and wipe with you finger then use a damp sponge for a smooth finish.
The key is small amount, there's no need for any of it to be on the walls, just in the crack.

I doubt it---All corners cracking? The same flawed technique was used on all corners--

these are the 'usual suspects' with corner failure--

Improper attachment of corner bead--not properly nailed or stapled

wrong mud used--best choice powdered easy sand---

Bad framing--missing doubled outside studs

wet lumber---this causes nail pops and seams to open also--I doubt this is your problem.