I have a usb2 recording interface. When I record my first two tracks (vocal and guitar) the sound is perfect and in synch. My buffer is set to 4ms right now, so when I sing the second track it is 4ms behind. How do I adjust for this?

I'm using ableton live lite 8.2
50th Anniversary American Deluxe Strat 3-tone Sunburst
Crate XT120r Amp
Epiphone Valve Jr. w/ Jensen P8r
Boss DS1
Digitech RP300 MultiFX