Settings is your hub for customizing your instance and notifications. After clicking the gear icon in the upper-right hand corner of the window, a settings pop-out will appear.
General Settings
General settings gives you options for accessibility, tooltips, compactness, time/date settings, and print options.
Theme
You can change your instance theme with theme settings.
Lists
Here you can toggle wrapping text in lists on and off.
Forms
In the forms settings section, there are a couple relevant settings. Tabbed forms allow related lists and form sections to be organized into tabs. Related list loading should almost always be selected as With the Form, but this setting deals with when lists related to the form in question load.
Notifications
Notification settings are more complicated but the most often used. There are 4 options to edit notifications settings: