Good Morning:
There is warm water coming out of my Kitchen taps when using the cold water tap, & how do you fix this

Sincerely:

Marj

This is a classic bleedover. The hot water is bleeding into the cold side either through a faulty mixer
Or faucet assembly. Try shutting the hot water off under the sink and check it again. If you no longer get hot out of the cold side your faucet\mixer is to blame.

Single or two handle faucet (tap)?