//Update//
This is 100% a Windows 10 or Nvidia driver bug. Other programs like Notepad++ or Sony Vegas will have bigger text sizes in some menus.
A reboot will fix that problem.
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We have no idea, what could change the Font size of all Menu items.
Does this still happen, when you rename the config file (must be done while client isn't running)?
Possible path for the settings.db
Code:
%appdata%\TS3Client
C:\Program Files\TeamSpeak 3 Client\config
In case this does fix the issue: I would like to have a copy of that settings.db (please send it in a private message). I'm interested to investigate time into that problem. Maybe i can find the problem.
Info before you decide to send it: This file does not have your identity and passwords stored. But your settings, contacts, bookmarks, profiles.