Can’t add site logo image

Hi,

I’m trying to add a site logo to my wordpress.org site that is using the Fork theme. I’ve been into the template editor and I can add a site logo block, but I can’t see how to upload an image to use as the site logo. If I click on the site logo block I don’t get any image options at all, just the usual options to change the block type or move it around.

I have disabled all my plug-ins incase they were causing problems.

Thanks for your help