Hello @SILKE.GESSLEIN

Here is the answer to your questions

1) to disfix the header please follow the screen record there is the options in the theme
https://www.awesomescreenshot.com/video/2779357?key=179f57845b8f031d17380aa42b1324bf
2) license is only for one site
3) for query no. 3 can you please explain in more details with the reference screenshot

yes you can change the color for all elements through Additional CSS except for the cloud because it the background image

Regards,
Psink

Hello akeller1862

Can you please share your wp-admin login details?
please share through contact form https://themepalace.com/contact-us/

I guess something is missing in the customizer setting

Regards,
Psink

Hello Sjirk

Please follow the screen record – to remove the “From the Blog” title
https://www.awesomescreenshot.com/video/2766000?key=7c086895977c2bec96c94bd60fba1c3f

Have a great day

Regards,
psink

Hello CaseyJ

We have released the new update. Now you will be able to active header image on a single page too

You will find the option “Disable featured image in header banner” inside customize >> theme options >> single post

Please update the theme

Regards,
psink

Hello Sjirk

Please follow the screen record – to short the homepage sections
https://www.awesomescreenshot.com/video/2757261?key=127f5f1369e35d519c040921753485dd

there is an option in the theme to short section

Regards,
psink

Hello Dilara,

Please Add this CSS in the Additional CSS

.site-title a{
    font-size: 25px;
}

.site-description{
    font-size: 20px; 
}

h2.entry-title {
   font-size: 25px;
}

Please adjust the font size value as per your need

Regards,
Psink

Hello Adrian

Please Add this CSS in the Additional CSS – to reduce space between main content and footer

.spacer {
    display: none;
}

Please add this css – to reduce space between header and main content

.cloud-background.page-section{
    padding-top: 50px;
}

Regards,
Psink

Hello CaseyJ

Yes, the header image for the single page is set as the feature image of post/page. So you don’t want the feature image at the header.

Can you please confirm that you want the header image to remain same for all pages?

Regards,
Psink