Hey jayyy,

I believe it's simply a matter of preferences. I'm short and right-handed. I rest most guitars on my elevated right leg when seated. However, when I play larger guitars (Dreadnaught to Jumbo) it's much more comfortable to rest the guitar on my elevated left leg, mostly because of an exaggeration of the "shotgun" positioning that necessarily accompanies the playing of larger guitars.

There are a lot of physical factors that go into determining what position is right for any individual. Such as a person's height, body build, abdominal girth, joint injury, arthritis or deformity, spine flexibility, arm length, bony deformities, etc. Then there's preferential chair height and optional use of a foot elevator.

So, I don't believe there is such thing as a universally correct technique for holding a guitar, sitting or standing.

Nicolai