sounds like you are describing oversteer not understeer.
Understeer: your front tires slip and car goes out toward the outer edge of the turn (feels like it doesn't want to turn)
Oversteer: your rear tires slip out as you turn too fast (feels like car turns too much)
either way, means you are going too fast for the turn and should slow down more before entering the turn. Always brake in a straight line before entering a turn.*
* there are of course exceptions to this rule, for advanced drivers and drifters who want to oversteer.