For me it depends on the knife.
The Rambo II knife (in the seldom occasions when I carry it hanging to my belt, because usually it is attached to the backpack) stays on the left / rear side (just like I used to do with the bayonette when I was in the army).
Otherwise, I used to carry a regular outdoor knife on the right / rear side.
But the fixed blade I carry the most nowadays is my Komondor and this one stays on the left / front side, at 45°, handles forward.
The Rambo II knife (in the seldom occasions when I carry it hanging to my belt, because usually it is attached to the backpack) stays on the left / rear side (just like I used to do with the bayonette when I was in the army).
Otherwise, I used to carry a regular outdoor knife on the right / rear side.
But the fixed blade I carry the most nowadays is my Komondor and this one stays on the left / front side, at 45°, handles forward.