Please sort your server issues first because we are unable to open your site. We tried to open above site on different computers and it's just loading and nothing happens.

the picture behind the Menu should be the slider, I set it in the page options under layerslider where you can choose between existing sliders. 

menu item color is exactly the same as hover background and that's why item text is invisible. To change it's color, you need to use below css:#Top_bar .menu > li.current-menu-item > a,

To move the sticky menu down, please use:#Top_bar.is-sticky .logo { height: 125px !important; }

For some reason the text has stopped displaying on the menu when it is selected or hover over.

and now, How can I down menu in the sticky mode? http://www.grupounifema.com/test2/   

Everything works, but I can't reach the theme option pagehttp://www.beckerhaeusl.at/wp-admin/themes.php?page=muffin_options

yes, you can use menu link with external link of course. You can do this the same way as you already made one page links.

http://themes.muffingroup.com/betheme/documentation/doc-images/menu-edition.png - this is an example of how to create one column. So if you want 6, you need to do the same 6 times.

I created a Layerslider with 1920x600px, but it behaves really odd if I insert it into the Homepage of the website. It just starts at the beginning of the page and not under the menu. 

My home page is in style "onepage" and the menu has anchors. And I want to create a outpágina that contains unique content, you can put a different menu on this page?

Really? I can open it.

1. I am using the Betheme Photo for the website. I am trying to change the text color of the menu. I change the color but it doesn't actually change the color of the text. I am using the One Color Ski

For Mega Menu columns you must add each menu item using a # "URL" attribute and - as the"Navigation label" value. Under the empty columns you can add the correct me

If i pay with Paypal and return after payment process back to the confirming page, the system shows me the following warning.

In reference to 2nd question, menu does not look good because you simply imported different demos several times and it's the most proper behave. If you want to have clean installation, you need to use

1. No, it is not possible. Language menu is reserved for WPML plugin.

Just to be clear, I want to Disable the Scroll Bottom Anchor

Also the menu items look all scattered.

How can i use the "secondary menu"?