Missing Logo on Site pages

Good day

On our Microsoft 365 SharePoint home page we have a nice looking logo at top left:

Nice!

But on the various site pages we just have a 'broken' image:

Not nice!

I think I know why this has happened (I reckon that rather than a file upload, the logo is a URL pointing to our old website*, but now we have a new website that online path to the online logo no longer exists) but what I don't know is how to correct it.

Can anyone advise where I need to go to fix it (recreating the path on the new website is not an option, by the way, due to the very different CMS in use and the file/folder structure around it)?

Thanks in advance

Jeff

EDIT:

* I've since confirmed, by right-click -> 'Copy image link', that this is correct.