recording from Yamaha synth

i have connected my Yamaha Syth to a Lenovo laptop via a USB. I record 1 track (e.g. drums), then, to record a second track (e.g. piano) i use the overdub so i can hear the first track as i play. But doing this records the FIRST track as well as the second, so i have drums and piano on the same track, so i cant move them around individually or alter them separately? Can anyone help? Thanks.

It is unusual for Yamaha synths to send audio over USB. Please check the manual. My guess is that you are actually recording from your laptop’s microphone.