By default, when you create an issue using the 3D Pin feature or the PDF markup tools, the issue will automatically be linked to the file. You can also manually associate an issue to a file as follows:
Click on the issue you wish to associate with a file. Scroll down to the section titled ‘Associated Files’. Click on the ‘Add a file’ field and a list will appear of the files within that project. Click on the desired file to associate it with that issue. This allows you to filter issues by file from the issue list and dashboard pages - useful when determining what’s blocking the release of a file.