How do you change out the little drain switch that you flip up or down to let the water stay in the tub or let it out of the tub? My husband unscrewed the screws but the piece would not come out.

Lowe's Home Improvement: Buy Kitchen Cabinets, Paint, Appliances & Flooring Here is the how-to page from Lowe's. It has pictures and instructions on how best to get it out.
Good luck with it

Westnlas... your link did not work for some reason... only brought me to Lowe's website ;) I think this was the link you were referring to!

Repairing Tub Drains

KARLIJO:

First...why are you doing this...? Clogged drain? Chrome has gotten ugly and you want to replace the trim? Let me know... OK?

It should be as simple as removing the screws and then giving it a good YANK up to dislodge the internal guts (see picture below).

Usually a two-phase pull... 1st dislodges unit and then second yank bends the inner rod so it can angle as needed to finally pull up and out.

Putting back in will be similar issue... will feel resistance and will need to almost bend the rod a little to get the unit back in, then should just fall into place after that.

Does your drain have a pop up stopper (not the trip lever now... the POP UP drain) or no stopper and just a screen where water drains?

Hopefully this information will help you... but if not, get back to us with more information... such as a name on trim plate... or even a picture if you can post it.

Don't forget to check the link above...info. is at the bottom of the page...may prove helpful!

Let us know... MARK