I have a newer two story house (built in 2001) with two bathrooms on the second floor. In bathroom A, the water pressure in the shower decreases the more I turn the faucet handle toward the cold setting. In bathroom B, I get the same thing the more I turn the handle toward the hot setting. Not so much of an issue in bathroom A, but in bathroom B it’s almost impossible to take a shower because the water pressure is so low. I’ve switched the faucet cartridges between the two showers to see if that was an issue but I get the same thing. The sinks in both bathrooms have very good water pressure for both hot and cold. What could cause this situation and how do I correct it?

I have a similar problem. I 'fixed' my issue by getting a low flow shower head. Seems like a full shower... just using less water. Worked for me. Your mileage may vary...