If you have a 4-line display you can set it to 4 line mode, but the 2-line home is fixed to the Pit/Other layout. There's also bignum but that only shows one probe always.
If the heatermeter is in front of you, the pit probe is the first jack. Also, if you use et-732, don't put them in all the way, only put them in once it clicks in. About 1/16 inch out or until you see a reading on the Heatermeter.