how to make scroll bar remain on screen

I have a new MacBook Pro but have been using Macs since the early 90's. This one has a scroll bar feature that sometimes disappears immediately upon opening a page. Is this a preferences issue? I often have to use the up and down keys to move up or down a page and sometimes, like now, that doesn't even work.
Thanks for the help!

Mountain Tweaks can make the scroll bar permanent, they also do Lion Tweaks, a version if you have OSX lion 10.7 installed