Hi Odd,
Thank you for querying in this forum.
From your description, it seems that you want to customize the template list in the drop down, and you found that you cannot see the template you used in the list.
May I know if my understanding is right? If so, we have tested it on our side with the latest version of OneNote 2016, and we went to Insert > Page Templates > and we saved the current page as template, we noticed this new template will not appear under the drop down list, as shown below:
However, the old template shows here, if we deleted the old template, this old template will disappear from the drop down list.
And we have also tried restarting OneNote and it still didn’t show the new template in the drop down list.
We’re sorry that it doesn’t meet your requirement, we do understand the inconvenience caused and apologize for it.
To address your concern, we’d suggest you go to OneNote > File > Feedback and provide your feedback. This feedback will directly go to them so that our related team can hear your voice on this feature directly.
If the scenario above is not consistent with yours, you can also post back and provide more details about your drop down list. May I know if you are using OneNote 2016 or OneNote for Windows 10?
Your understanding and patience will be highly appreciated. I hope that you are keeping safe and well!
Best Regards,
Sukie