Wanting to Add MultiSite, Have to Change WWW

I just went through and added multisite to my website, but because my site is www, if someone typed in summitforwellness.com then it would revert to some kind of sign-up redirect instead of the home page. I ended up reverting back to a backup to fix everything back to where it was.

From what I am seeing, I need to change my site to nonwww to avoid this issue. If I do that, will it change other links on my site, such as feed urls for various feed syndicators? I am wondering if apps and whatnot that are pulling from https://www.example.com/feed (or whatever feed url) would no longer work correctly.

In addition, would any internal links on my site that are going to https://www.example.com no longer work as well, or will it automatically be redirected to the correct link?

Finally, how do I change from www to nonwww? I thought there was a simple way, but I can’t find it (I’m not too crazy techy, but can fend for myself slightly).

The page I need help with: [log in to see the link]