Updating is straightforward. The official recommendation is simple:

Help you about the final days of the classic version. Let me know how you'd like to proceed.

: The ability to post YouTube and SoundCloud clips directly into chat feeds. Post-Sunset Options

To enjoy the performance of Build 807 without the application silently forcing a patch to the latest modern client, redirect the server update checks:

I can provide the specific step-by-step instructions you need! Share public link

Are you looking to settings to the new version, or are you trying to find a way to keep using the classic interface ?