In the welcome page, you can check what Url is included as a hidden parameter. It is encoded with Base64.
In your case, it has aW5kZXgucGhwP0l0ZW1pZD0yNjM=. You can decode it (http://www.motobit.com/util/base64-decoder-encoder.asp) and get "index.php?Itemid=263"
If you need to define a return Url beyond the module parameters, you can just define a module override and fix the Url.
You can find the original layout in modules/mod_login/tmpl/default.php, and the return parameter in line 166.
Ref: Module Layout Overrides https://docs.joomla.org/Understanding_Output_Overrides#Module_Layout_Overrides