When launching PDFs from Joplin, the system e-book reader is opened.
I would prefer to use the normal Ubuntu PDF viewer.
Double clicking a PDF from file explorer launches normal Ubuntu PDF viewer, but Joplin does not.
I can't find any configuration to control this behaviour.
Thanks for your response, but unfortunately this does not resolve my issue.
As indicated in my original post when I check the OS settings I can see Ubuntu opens the correct application for PDFs. It is just Joplin that opens the wrong one and I'm not sure why.
I was hoping there was some config in Joplin I'd missed that someone could point me towards.
After removing GIMP, Joplin launched Chrome for PDF viewing.
I believe I have resolved now. Solution was embarrassingly simple.
Right click a PDF in file explorer and click "Open with..." to select a launcher.
"Document Viewer" is default selection.
Pick any other option (I picked Chrome) and click "Always use" at the bottom.
PDF launches in Chrome.
Close Chrome.
Right click a PDF and switch the default back to Document Viewer.
PDF launches.
Close PDF.
PDFs launched from Joplin now open in the default PDF viewer.