Hello Daniel,
Thanks for writing in!
You are using Ethos stack. Please go to X > Theme Options > Ethos to adjust the background color. And then for you navbar, I can see that you are using UberMenu. Because of that, you will need to go to Appearance > Ubermenu > General Settings to change the background colors.
Meanwhile, X Theme 7.1.2 is now available in automatic updates! This release contains fixes for several issues, like you have mentioned above, so be sure to check out the changelog (https://theme.co/changelog/). Please do update to the latest version. After doing the updates, always remember to clear all caches when updating so that the code from the latest release is always in use. This will help you to avoid any potential errors.
Best Regards.