The Screen tab, Customize tab, Performance tab, and the Hours Display on the General tab apply only locally. The rest of the Preferences settings are database-wide.
Screen [1st tab] and Customize [5th tab] preferences apply only to each individual computer workstation, even if on a network. The Screen tab defines local settings and the Hours Display at the bottom of the General tab determines the format for entering hours as set per workstation. The rest of the tabs [General, Reimbursement Limits, Date Limits, Country] define preferences in the database throughout the network.