How do I get my videos to rotate to landscape when turn my phone sideways.

All of my videos seem to be locked in portrait mode

I don't know about Android phones.  But iPhones have a feature to change screen between portrait and landscape mode.  Along with that feature is menu button that will lock the screen in whatever picture mode it currently is in.

You might try getting phone in landscape image display, and if possible locking it in that mode.

I have seen cases where that does not work, and you have to exact opposite.  Information stored with image file is either corrupt or phone does not read information correctly.

are you talking about in the shooting moment or in post?
In post it is easy to correct it with Premiere pro for instance.

https://www.wikihow.tech/Rotate-a-Video-in-Adobe-Premiere-Pro

HedgeTrimmer Posted at 2018-5-19 08:06
I don't know about Android phones.  But iPhones have a feature to change screen between portrait and landscape mode.  Along with that feature is menu button that will lock the screen in whatever picture mode it currently is in.

You might try getting phone in landscape image display, and if possible locking it in that mode.

I am using an iPhone X .. .and eureka ... Your suggestion worked... Thanks!

The Mavic Pro Remote Controller has a button on right side of the display screen and if you click it to the right and left it will adjust the image from landscape to portrait and back again.