David,
I’m in the same position as you in being unable to change the splash screen image on Windows. Like you, I tried swapping in a different image with the name “slide1-scaled.jpg” but the standard image still appeared on startup of PL5.
In the same folder there are some .HTML files, including en.html - examining this with Notepad shows it has a reference to slide1-scaled.jpg. I thought about editing this to refer to a different image, but when trying to save a copy of en.html by remaining it I get a warning that “it would no longer belong to the folder en_files” so I abandoned this, not being sure of the implications.
I did take a copy of the en_files folder and en.html file and place them in a temporary directory so I could modify them without concern. When I open the en.html file with a web browser (e.g. Chrome) it displays the slide1-scaled.jpg image. I can change either the filename referenced in en.html or the image file in the en_files folder and opening up en.html in the web browser then brings up the changed image.
Perhaps someone with more knowledge of Windows, and more free time, can enlighten us.
My only other thought was to uninstall PL5, reinstall it and replace the image file before first launching PL5 - in case the image is being cached somewhere or held in the PL5 database. However, as this seems to be a case of “a sledgehammer to crack a nut”, and I’m not that motivated to change the image, I’ll leave this for now. I might give it a go when the next update of PL5 comes out,as I’d be doing an install anyway.