Dear jet hays
Welcome to Microsoft Community.
We apologize for the inconvenience caused. Currently, the Aptos font is only set as the default in the preview version of Office. In the official release, it only appears if the "Connected Experiences" option is enabled, and it does not become the default font. However, in the preview version, even if you disable all options under "Connected Experiences", the Aptos font remains the default.
To avoid further disruption, we recommend opting out of the preview program and switching back to the official release of Office. This is because modifying templates in PowerPoint currently has no effect—even after changing the slide master, new presentations still default to Aptos.
Additionally, you mentioned: "Also your notices etc. are in it as well." Could you clarify whether this refers to in-app notifications or system-level messages? If it’s system-related, have you also updated your Windows OS to a preview version? If so, we suggest temporarily reverting to the official Windows release as well.
To switch back to the official version, you’ll first need to leave the Office Insider program. You can do this by opening any Office app, clicking "File" in the top-left corner, and following the steps highlighted in the red boxes and arrows in the reference image below.

Then uncheck all selected options in the dialog box below, and click "OK".

After completing the above steps, the next step is to roll back the version by performing the following operations:
- Open the link and find the version you want to revert to, such as the October 31 version, and make a note of the version number: 18526.20168

- close all the Office software, in the "Start menu" in the search for "Command Prompt" (or "cmd"), right-click and select "Run as administrator";
- In the command prompt, enter the following code after the carriage return
cd %programfiles% \Common Files\microsoft shared\ClickToRun
- Then type
Officec2rclient.exe /update user updatetoversion=16.0. 18526.20168
18526.20168 is the version number of the version you want to roll back to.
The download can take a long time, in our tests we successfully reverted to an older version after an hour of downloading.
If the above rollback steps don't work, you'll need to uninstall Office and then reinstall the official release. Before reinstalling, if you're using Outlook configured with IMAP or POP protocols, make sure to back up your data first to prevent any data loss.
Best Regards,
Yujun.F-MSFT | Microsoft Community Support Specialist