I've noticed recently that pdf files provided by client have got indexed with weird and random title tags when searched for in google (site:mysite.com/path-to-file.pdf). Now I've tried to change it with yoast plugin by changing the seo title tag and sending for reindexing around two days ago, but it seems it didn't change yet.
Is my aproach correct to changing the google search title for those files and I just have to wait bit longer or is there something else I should have done?
Google also pulls information from the PDF file itself. To truly fix the files, you'll need Acrobat Pro. You can then edit the embedded title, and you then delete the original and upload a new one.
If these PDFs are associated with specific Posts or Pages, it's safest to go to that individual Post or Page editing screen, delete the link from the content and the file from the Media Library there, and upload the new PDF on that editing screen, because WP will automatically place it in the same month folder it was in before (when on the edit screen it goes into the month the Post/Page was originally published). If you just go straight to the Media Library to mass upload, WP will upload everything to the current month's folder, thus breaking links even if you named the PDFs the same filenames.
