Promotion Headline Issue

Hi, I want to know, if it is possible to change the title of the promotion headline in a image? I tried in the customizer as you can see in this picture and it worked in the preview. I saved it, but when I refresh the site, it changed to the custom theme promotion-line and I can't find a way, that this picture is replacing the line? If it is not possible this way, then maybe it is possible to change the font family, just of the first line? I found only a way to change the font-family of both lines... Maybe you can help me in this? Thank you!