Where to buy door knobs/lever handles at a decent

I have a mold problem on almost all my window casings in the winter. They are made of wood and moisture builds up on the windows during the winter. I live in a tri level and this problem is on the main floor and the upstairs but not in the downstairs family room. We have put in a new furnace with humidifier and air purifier on it but the problem is not solved. Any suggestions would be greatly appreciated. Thank you.

Hello, Have stripped down the garage doors (4) and also have two entrance doors and a window in a detatched workshop at a house we recently bought. Am installing fiber cement trim and siding planks. On the garage doors and windows (overhang on sofitts is 2'), I'm assuming that flashing is the right way to go, although I recently saw on some do-it-yourself show on TV about a "rubber" flashing made by "Grace" that looked real easy to install instead of traditional galvanized or aluminum. I am also surmising that just adding calk to the joints isn't enough. Some advice on what is right would be most appreciated. Thanks, Hopro Deland, FL