Lots of beginners seem to be confused by the topic of device selection by the original remote of combo devices.

Typically a device select key on the original remote does two seperate operations:

1) It send a signal to the actual device to tell it to change modes.

2) It changes mode within the remote itself, which affects what the remote will send for other keys.

Without JP1, a device key in an OFA remote just does operation (2).
If you want one key to do both operations, you need a macro, and without JP1 you can't assign that macro to a device key.

In other RC forums people complain about trouble using learning to duplicate such keys. It should be obvious that (1) is a signal actually sent by the original remote which can be learned by a learning remote, but (2) is something internal to the remote. It isn't sent so it can't be learned (I'm amazed at the trouble people have understanding that point).

For a specific select key of a specific combo device, you want to start by understanding what the original does. While most do (1) and (2), some only do (1) and some only do (2).

If you think about all the effects of pressing the key normally, you should be able to work out a test based on pressing the key while covering the IR emitter (so the device doesn't get any signal) that will tell you which subsequent effects are due to a mode change in the remote vs. which are due to a mode change in the device.