I just noticed no one had responded to your message. Are you still experiencing the problem?
If so, please clarify if you are using the web browser version (as apposed to the Gospel Library app on mobile devices).
Assuming you're using the web version...
There are often times problems with the web version where it thinks you're not logged in even though you are. Pretty much every day I sign in to the church website (nowadays I have to sign in twice at the main page to be really signed in). Then open up gospel library and navigate to some content. Highlight something. You'll get a popup and be asked to sign in. Press the button and then you should be signed in and you can actually use the annotation tools, see previous notes, etc.
Now, another frequent problem on the church websites is that you need to clear your cookies. When things don't work correctly, try clearing your cookies then try again. Many times that fixes things (I haven't tried yet, but clearing cookies might fix the second login I've had to start doing recently).
If you do all that and it still doesn't work, come back here and tell us your platform (Linux, Mac, Windows) and which web browser(s) you're using