I have two Windows 8.1 computers with USB wired mice (1 for each computer). The computers are only connected via an internet router (1 wired, 1 wireless). If I change the primary and secondary buttons of the mouse on one computer (Control Panel: Mouse:) they also change on the other computer. Any idea why and how I prevent this? I've not noticed this interactivity with anything else.
(expanded from comment)
I have a feeling microsoft saves your settings to your ms live account (may be called something different - I don't use windows) and apply them for all computers you log in on. Similar to the way that signing into Google Chrome will load bookmarks and plugins on a previously unused browser.
From here (my emphasis):
When you sign in to your PC or device with a Microsoft account, you can get apps from the Windows Store, back up all your important data and files using free cloud storage, and keep all your favorite stuff—devices, photos, friends, games, settings, music, and so on—up to date and in sync.