I have 3x 3.6ohm 10” subs. I have 2 wired in series to create a 7.2ohm load then paralleled to the third sub to create a final load of 2.7ohm. But the problem I’m having is is the two subs that are wired in series don’t seem to move as much as the third. Is there a reason for this? Is there any other way I could wire them. I need to create a load no lower than 2 ohm while also not high than 4 ohm.

The sub that's paralleled is getting four times the power than either of the others, that's why it's moving more. In this suituation your only option is to wire them all in series, or get an amp that's 1 ohm stable.

Buy an extra sub or drop a sub.

I'll show my working;

let's assume the amp is outputting a 20v signal, we'll also assume it's a perfect voltage source and doesn't drop under load.

The 2 subs in series present a 7.2 ohm load to the amp, to find the current flow we divide the voltage by the resistance, so 20/7.2=2.77A, to find the power we multiply the voltage by the current, so 20*2.77=55.4w, we divide that by 2 sinse the power is shared between the 2 drivers, so 55.4/2=27.7w per sub.

So now we look at the lone sub in paralell, it presents a 3.6 ohm load to the amp, to find the current flow we divide the voltage by the resistance, so 20/3.6=5.55A, to find the power we multiply the voltage by the current, so 20*5.55=111w.

All 3 subs in series, 20V/10.8 ohms=1.85A, 20V*1.85A=37w, 37w/3=12.3w per driver.

2 subs in paralell , 20V/1.8 ohms=11.1A, 20V*11.1A=222w, 222w/2=111w per driver.

Your best option is to run only 2 subs in paralell, since that will draw ~6 times more power from the amp than 3 in series.