Please HELP 404 error after changing site name in settings

I am brand new to doing this.

I could see the theme and edit the page but it did not show up as my page, https://www.happiness1st.com. It had all these additional words after the page and when I typed https://www.happiness1st.com it would just show me that hostmonster.com was my provider.

I went into settings and changed the second URL to my home page and then the theme began showing up but I had a 404 error for the content which was not showing up.

So, then I went back into settings and changed the 1st URL to my home page thinking that would get my content to show up there.

Now all I get is a 404 error. I can’t get back to where I could change anything.

Please help. Thank you ever so much!