Computer mouse problem... i think...?

Okay so, a while ago I set this setting thing... so that when i scroll over something on my desktop (example: My Computer) it underlines all the words and it's basically like clicking once on a normal mouse setting. And it's starting to bug me... so does anyone know how i set it back to normal? I know it's a little confusing but yeah... Oh yeah! and if it matters, i have a microscoft computer.. Please help me! =O