Yup - the 5e is a one-model-only transmitter. To use it for multiple planes you must bind it to the new plane when you want to use the new plane. If you fly one model for "the day" then bind that model and fly it.

The bind plug needs a 3 wire connection to the Rx. Typically that's accomplished using an external charge port / battery switch that has 3-wires connected to the Rx. The 3-wire connection to the Rx allows you to insert the bind plug into the charge port to bind the Rx.

Do you have an open channel on your Rx? if so, you could use a 3-wire extension (3 in or 6 in) and plug the male connector into an open channel on the Rx and leave the female connector free in the fuse. That way, rather than having to remove the Rx to rebind, just insert the bind plug into the female end of the exposed extension.

If you don't have an available channel "MAYBE" you could use a 3-wire "Y" extension. Plug the male end into an existing used channel (throttle?). Plug the throttle servo wire into one end of the "Y". Leave the other end of the "Y"fee in the fuse. Then you "MIGHT' be able to insert the bind plug into the exposed leg of the "Y" to bind the Rx.

HTH