The bathroom fan, does it blow or suck? If the wires are connected in reverse, the fan will blow the air (moisture)back into the room.
Do you have a range hood that vents to the outside?
The key to all of this is ventalation. Once you have removed all the water from the bathroom and kitchen areas, you need to look for any other means that water could come from.
FYI, The average person will breath out about one pint of water while sleeping. (No, that is not a reason to live alone).
Read your warranty information that should have came with the windows, most MFG's include a statement about condensation.
Also, get a dehumidafier for the upstairs.
Good luck,Jason PS. If you are emptying the dehumidafier in the basement every day, that is alot of water.
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