DGS 101852874, most images can't be attached, why?
I'm guessing that it's because these images have been indexed? There are many names on image 19 that were not indexed. I would like to attache the image for Agnes Sprague.
The data structure on FamilySearch is extremely index-centric. One consequence of this is that if there are any index entries associated with an image (no matter how incomplete or inaccurate the index is), the "Attach to Family Tree" button is made unavailable. However, you can still attach the image as a source, in two different ways.
The first way creates a "local" citation, meaning it has the same tree icon as other FamilySearch sources. To use this method, click the Source Box button on the image and choose Add to My Source Box. (This will result in an immovable pop-up window right in the middle of your screen, so you may want to first open the image again in another tab, for reference.) Fill in the title and any notes and click Save to put the citation in your Source Box. You can then attach the citation to the desired profile(s) starting either from the profile or from your source box.
The second method creates an "outside" citation, meaning it will have the globe icon as if it came from some other website. To use this method, copy the URL of the image, then go to the Sources tab of the profile. Click Add Source, and choose Add New Source. Paste the URL into the appropriate field, then fill in the title (required) and the rest of the fields (optional). If you want to attach the same citation to more than one person, make sure the "Add Source to My Source Box" option is checked before you click Save.
Either method will result in a permanent link to the image, along with whatever you type in for the associated text. The Source Box method will have FamilySearch's auto-generated citation format; the URL-based method will have whatever you come up with for the citation.
You can still add a new Source and use the URL of the image or do the same in Source Box. It probably won't permanently link the image - because as you mention - it isn't indexed in the system.