All corners cracking
 

Would the fact I live 800 ft from the railroad tracks be the cause to my homes wall corners cracking? The trains come by about every 10 minutes.

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.