The system comes with several pre-defined themes that you can select to change the overall screen visual styel presentation. Once a theme is changed, it will automatically be used the next time you log-in. Each user can have his/her own theme. To change a theme, just click on the theme roller toolbar or if visible click the the Theme roller dropdown on the sub-menu.
Below is a screenshot changing the theme to Office2013DarkGray and then to Material using Theme Roller dropdown list and the theme roller toolbar , respectively.