Which browser are you switching to?
If you're switching to FireFox, to make that
your default, go to Tools>Options>Main Tab
On the bottom of the window, there's a default settings and check the box to make sure that it checks to keep FireFox the default browser. Then click on the button next to it, "Check Now".
If you're wanting to make sure IE is your default, if you've used
FF at all, make sure that box is unchecked and open the IE browser. Click Tools>Internet Options>Programs Tab
About 2/3 of the way down, there is a box to check and then click on "Make Default".
If there's another browser you are looking to make your default, let me know.
"I would feel more optimistic about a bright future for man if he spent less time proving
that he can outwit Nature and more time tasting her sweetness and respecting her seniority."
E. B. White (1899 - 1985)