There are four ways to change settings or access various options when using Windows 8 Apps

 

Firstly on the charms bar - which you can access by moving your mouse pointer to the top or bottom right corner (or swipe in from the right of the screen if using a tablet) - and selecting Settings

 

 

Secondly by right mouse clicking anywhere in the app (or swiping up from bottom of screen if using a tablet)

 

 

Thirdly by clicking the icon shown below which will appear in the top (or bottom) right corner of some apps

 

 

And finally by pressing the following key combination

 

+ Z