Hello Klaus,

I am really sorry for the delay of this reply as it is actually a long weekend for us here due to 2 separate public holidays. I can't seem to access your site with the provided login credentials at http://screen.stackideas.com/2015-05-04_1435.png .

By the way, the reason that all the text are uppercase is actually because of your Joomla template. It seems like they have added a css rule that enforces all text to be capitalized. Please see the codes below,

#s5_menu_wrap li a, .S5_submenu_item a, .button, label, li.s5_am_inner_li span.s5_accordion_menu_left a.mainlevel, #s5_button_frame ul li a, .btn, #s5_login, #s5_register, .pagenav a, #s5_drop_down_button, .uppercase, #s5_responsive_mobile_drop_down_menu, #s5_responsive_mobile_drop_down_menu a, #s5_responsive_mobile_bar_active span, #s5_first_bar li, .inputbox, .registration input, .login input, .contact-form input, #jform_contact_message, #mod-search-searchword, input, textarea, #s5_breadcrumb_wrap, a.readon, .article-info, .tab_show_text h3, .readon_lines {

    text-transform: uppercase;

}

It's best that you check with them and see if there's a settings in the template that could disable such behavior?