Correcting size of page in public view after changing themes

I’m a newbie. I changed the theme from Thanks, Roy to Emiglio. But when I look at the public view, the page does not fill up the screen like our previous theme did. How do I correct the size?

Can you share a link or screenshots to clarify what you mean?
Have you tried a hard refresh in your browser, or looking at the pages in a new browser?

This is how my new theme shows up on the screen.

The old theme was set up by a previous staff member, and I’m the one taking over with very little background in this.

Thanks!

Both of those themes look to be functioning normally. The differences in the width of the content have to do with differences in the themes. Other themes, like Berlin and Rhythm, also have that sort of width.