I am afraid you must either link your theme here or ask the theme developer.
There are two ways a theme might create a homepage and only knowing how this is done we can help you.
- with lots of config and maybe some content in
data/homepage.ymlor similar files. - with
content/_index.md.
If it’s 2, you move that file to content/about/index.md, and that part is done. If it’s 1, you must move that whole configuration into a markdown file, or your theme’s developer will have a switch that moves things around.