Dear Maddoctor,
If you can provide us your site URL, we will observe and can provide you with possible solutions.
Best Regards!

Dear davidrogut,
Here are the possible solutions for your query:-
1.For logo issue in mobile, please add this given css in additional css of customize.

@media only screen and (max-width: 767px){
.custom-logo{
      width:200px;
}
}

2. Please increase header image height for given path (Appearance > Customize > Header Options > Header Image ) .Steps:-
– Select “Background Image” from header image display options after that scroll down then there will a inner height options, please increase it
– Please follow the attached images for references.
Step 1: http://tinyurl.com/y5vhmtcl
Step 2: http://tinyurl.com/yyt7n9s8

Dear thaddsky,
This feature is available only in the premium version of Fitness Hub.
Best Regards!

Dear eescobar90,
Our developer team shall observe your issue and provide you with possible solutions.
Best Regards!

Dear Atuser,
Our developer team shall observe your issue and provide you with possible solutions.
Best Regards!

Dear Rouven,
This feature will require theme customization.

Best Regards!

Dear Rouven,
Please follow the path below to change header image individually for each page.
Appearance > Customize > Header Options > Header Image
There you can click on Add new image and upload images you want.
Click on Randomize uploaded headers and publish your site.

Best Regards!

Dear eescobar90,
Please follow the path below:
Appearance > Customize > Header Options > Header Image
You can adjust the height of the background image there to solve the issue.
Best Regards!