Probably true in most "regular" cases, but definitely not true of everyone. I get far more reflux in fact when I sit upright, because I think the way I sit puts pressure on my stomach and pushes up the contents. I also have a hiatus hernia so it probably makes that worse too.

When I want to relieve it I actually lie down on my right hand side, on an incline and do some deep diaphragmatic breathing. That works most of the time, and much better than standing or sitting upright.

If you have burning in your throat, then there isn't really much else it could be besides reflux.

I agree. Most of my discomfort comes when I am upright. I hardly ever get it when I'm laying down.

I thought maybe the burning in my throat could possibly be post nasal drip. Wishful thinking.

I know of a cheap device for reflux/throat problems, but it seems to be more suitable for night-time refluxers as it looks rather strange, so not sure how useful it would be for you

http://www.rezaband.com/

There is also reflux surgery if it is really affecting you, though that is a far more invasive and isn't without its drawbacks.