Once I set the zoom setting to my needs can it be made a default setting size and not change back to a smaller size every time I move to a new site?

I have Windows 7 on a 17 inch Alienware. The web pages are too small on the default screen resolution settings I use for my work. I have to zoom up several clicks in Firefox to enjoy reading. Every time I change to another site it reverts back to the smaller size and I have to re zoom again. Once I set mt zoom preference it should stay that way. How can I do this?