LFE and Line refer to which input you used to connect the sub to the receiver. LFE should be the setting that bypasses the sub's internal xover, which is what you want if you are using the bass management in the receiver. If that is how you connected, then use the LFE phase control.
You want the phase setting that sounds the best at the listening position (usually the correct setting will be the loudest). If the sub is behind you, there is a good chance that 180 will be correct but you have to try both and see which one you prefer.
