Hey SileeBailey,
To make the button white with gray text, Please try this code in the General Styling > Quick CSS field:

#top.page-id-320 .av-custom-form-color.av-light-form.avia-mailchimp-form .button {
background-color: #fff !important;
color: gray !important;
}

To float the elements to the right, Please try this code in the General Styling > Quick CSS field:

#top.page-id-320 .avia-mailchimp-form #element_avia_0_1 {
float:right !important;
}
#top.page-id-320 .avia-mailchimp-form p.av-last-visible-form-element {
float:right !important;
}

Best regards,
Mike

Hi,
Glad we were able to help, we will close this now. Thank you for using Enfold.

For your information, you can take a look at Enfold documentation here
For any other questions or issues, feel free to start new threads under Enfold sub forum and we will gladly try to help you :)

Best regards,
Mike

Hi,
To remove the comments and comment number, in the backend, hover over a post title and click “Quick Edit”:

then un-check the comment box:

if you already have a comment in the post you will need to delete it.
About the sidebar, as you said, you know how to add a sidebar,

But where can work how the single post page should look like?

sorry I’m still unsure, but I think you mean that the “single author” layout with a sidebar has a small image to the left of the post:

but without a sidebar the image is in the center:

is this what you mean? If so please read this post

To show the back to top button on mobile devices, Please try this code in the General Styling > Quick CSS field:

.responsive #scroll-top-link {
    display: block !important; 
}

I tried your contact link in the menu from a few pages, such as IMPRESSUM, in mobile and seemed to work fine, please explain a little more. Thanks for your patience.

Best regards,
Mike

Hi,
I notice you have a few jQuery errors, so I removed the code to try to resolve these errors first, and cleared your cache.

function switch_mobile_columns(){
  ?>
  <script>
(function($){
  $(document).ready(function(){
  if ($(window).width() <= 766) {
    $(function() {
    $('#top.single-post.rtl_columns .post-entry .flex_column_div.first').insertAfter('#top.single-post.rtl_columns .post-entry .flex_column_div.el_after_av_one_half.el_before_av_one_half');
    });
    }
    });
  })(jQuery);
 </script>
  <?php
  }
  add_action('wp_footer', 'switch_mobile_columns');

Can we try disabling your plugins to find the error? Please print copies of your plugin settings in case the settings are lost when disabling the plugin.

Best regards,
Mike

Hi,
Glad to hear, we will close this now. Thank you for using Enfold.

For your information, you can take a look at Enfold documentation here
For any other questions or issues, feel free to start new threads under Enfold sub forum and we will gladly try to help you :)

Best regards,
Mike

Hi,
Please try this code in the General Styling > Quick CSS field or in the WordPress > Customize > Additional CSS field:

#top #header.header-scrolled .logo {
margin-top: 0px !important;
}

it will remove the top margin when the page is scrolled.

Best regards,
Mike

Hi,
Thank you for the update, we will leave this open to hear back from you.

Best regards,
Mike

Hi,
Danke, ich bin glücklich zu helfen. Wir werden das jetzt schließen. Danke für die Benutzung von Enfold. Zu Ihrer Information können Sie sich die Dokumentation hier ansehen . Für weitere Fragen oder Probleme, können Sie gerne neue Themen unter starten Enfold Unterforum und wir werden gerne versuchen, Ihnen zu helfen :)

— Translated with Google —

Thank you, I’m happy to help.
We will close this now. Thank you for using Enfold.
For your information, you can take a look at Enfold documentation here
For any other questions or issues, feel free to start new threads under Enfold sub forum and we will gladly try to help you :)

Best regards,
Mike

Hi,
I made some adjustments, please clear your browser cache and check.

Best regards,
Mike

Hi,
Very good then, thanks for using Enfold.

Best regards,
Mike

Hi,
Glad to hear, I assume we can close this now, but I want to ask anyways :)
Shall we close this?

Best regards,
Mike

Hi,
Thanks, we will leave this open to hear back from you.

Best regards,
Mike

Hi,
Please check our trouble shooting post

Best regards,
Mike

Hi,
Please go to Enfold Theme Options > Header > Extra Elements > Phone Number or small info text to show text in a small bar at the top. Then go to Enfold Theme Options > Header > Extra Elements > Header Social Icons to show social icons at the top.

Best regards,
Mike

Hi,
Here is a nice list: 9 Of The Best Related Post Plugins
Another option, I see that you only have a few post on your site, so if every page is going to have the same list of related posts we can copy your element from a default editor page and add it to your advanced layout builder page. This would keep the Enfold style.
Probably not what you had in mind, but I thought I would offer.

Best regards,
Mike