Uploading 4K video to YOUTUBE

Ill try to explain this the best i can so that i can get guided in the right direction. Im a small youtuber and i normally do GAMING related videos and upload through my PC and edit it through a software and then upload to YOUTUBE, but something came up and im recording videos on my Iphone 7Plus and i want to send them to my PC to edit through a software and then put it on youtube instead of Recording on my iphone 7plus and straight sending to YOUTUBE. How do i go about getting the BEST quality of my videos so that way when i send it to my email to use on my PC; the quality dont change. I want to be able to have my 4K on the video no matter what i do with it. I went on my youtube settings on my iphone and went to "Upload Quality''then selected "Full Quality".... But again, i want to be able to edit my videos before putting on youtube. So i need help to get the best that i can out of it.