Posting instagram videos in stereo (iPhone)

How do I post Instagram videos in stereo/high quality sound on IPhone? I keep posting on Instagram and it just makes my videos into mono. I tried many things. My speakers are not messed up or anything, I heard this problem is only on iPhone. Instagram is in the latest update, I post my videos on both YouTube and Instagram and Instagram’s sound quality is just bad. Nothing really works, and the only solutions I can think of is to get a pc or an android device which I cannot get right now.