Fast overlap save method
for overlap-save, (sometimes called "overlap-scrap") when you (circularly) convolve h with x1. you scrap the first 3 output values of y1 and keep the last 5 values.  when you (circularly) convolve h with x2, again you scrap the first 3 values of y2 and keep the last 5 values.

with

x[n]={7,6,4,5,2,4,5,2,3}
h[n]={1,2,3,1}


it should be

x1[n]={0,0,0,7,6,4,5,2}
x2[n]={4,5,2,4,5,2,3,0}


remember that in convolution, h[n] gets turned around to be h[-n] (h[0] remains in the same position but the other values are extended to the left).  only when h[0] is aligned with x1[3] will you get a legitimate value for y1[3].  and notice, because you (necessarily) delayed x[n] by 3 samples with that initial zero-padding, the output will also be delayed by the same amount.