There's a a few different techniques for mobile web content adaption. Depending on the technique used by the page you're analyzing you way need to set a user agent so the right page is fetched.
This is a companion discussion topic for the original entry at https://seotoolsforexcel.com/mobile-webpages-and-seotools/
I see this post is a little older so just want to make sure this is still update today. In the "Global HTTP Settings" under the "Request headers:" section there is now a column for "Name" and "Value". Is "Name" on the new version and "Header" like your screen shot above the same?
Thanks! You're always super responsive on here and it's very much appreciated!