User Preferences are stored in the User Preferences [sys_user_preference] table. Many specific user-based preferences are maintained in this table, which is structured very similarly to the System Properties [sys_properties] table. The main difference between a system property and a user preference, is that a user preference is associated with a specific user, whereas system properties affect all users.

One example of a user preference is the Compact the user interface toggle in the settings menu after clicking the cog icon in the top-right of the ServiceNow interface:

There is a user preference record corresponding to that change, called glide.ui.compact. Toggle this setting On, and then navigate to the sys_user_preference table (User Administration | User Preferences). If the Updated [sys_updated_on] field is not shown in the list view, add it and then use it to sort the User Preferences table so that more recently updated records show up on top. If you refresh the list...