thanks for asking. I initially started out with an 1.5 hr video in a project, to chop out pieces of it to come with a 5 minute video. I realized it was better to use the Trimmer with the full length in it and extract the segments to the main. So now I have the main Timeline lengthened out with an 1.5hr ruler in it. I was trying to make the main ruler 5-6 minutes to give it a more working perspective (and easier handling).
How about zooming in? Use the up/down arrow keys or the scroll wheel on the mouse. It won't change the end of the timeline, but it will let you fill the screen with smaller sections of the project.