How to make the music ruler smaller?

Whenever I compile my song, it's over an hour long because the ruler just keeps going?
 
What do I do?

scook
If by compile you mean export, after selecting the tracks specify a time range by either click-dragging across the time line or using the the Select From/Thru or By Time functions.

will try that now thanks

Don't call the export function until after selecting the tracks AND specifying the time range.

The time ruler has no bearing on the length of the project and does not affect the length of an exported file. The length of an exported file is determined by what is selected. Although not entirely necessary, it is a good practice to specify the time range when selecting tracks for export. Often there are events well past the end of the clips which are overlooked such as automation nodes or MIDI events which result in very long exports. Also, it is common to have several blank measures at the beginning of a project. Setting a time range can skip blank measures at the beginning and fix the end of the export to a specific measure.