I have found an old xsltListViewWebPart that displays images to resemble a picture library. I'm completely unfamiliar with xsltListViewWebParts and I cannot find an option where the source for the images is set. When I edit the webpart there's no field to specify a link from which the images are pulled. How can I change the source? Thanks a lot.
Found out the answer, duh! Pretty embarrasing but in case anyone is wondering as well...
Since it's a picture library I just had to insert the picture library webpart. This webpart is of type 'xsltListViewWebPart'.
The whole time I was under the assumption that I had to change the existing webpart's source to the new picture library.