As mentioned above - you have to assign a model memory to each receiver/model. The DX61 has 10.
Make sure you are in ACRO model type
Go to SETUP list
scroll to MODEL NAME
press the select (top of roller)
scroll to unused memory spot
select
the roller spins through the alphabet. When you get to the letter you want select it, then go to the next letter and repeat.
The instructions are non-existant in the manual - it never mentions how to "spell out" the name or that an alphabet feature exists. That's standard for all transmitters pretty much. But if this is your first . . .
I'm a Futaba fan and user but I got a DX6i for my electric foamies. A good radio for the price and I have had no problems. Added a backlight (on a new switch) for these old eyes. Note this is set to Model 3 -SE5A