Hi Leonard,
Unfortunately, using the (modified) voice recorded in a channel of a MIDI file as current voice in a Keyboard part is not possible.
You could go into Song Creator on the PSR-3000. There, in the tabs "1 - 16" and "SYS/EX." all important Voice parameters can be found.
You could also use the PC (Windows) program "MixMaster": Load the MIDI file in question there, then click on "List View", filter for the desired MIDI channel and, if necessary, filter out all events that should not be displayed. This way you could also see the Voice parameters used (similar to the one described above for the Song Creator).
Another option would be to play the MIDI file in a DAW or with a MIDI file player like "vanBasco" on the computer and control a Keyboard part of the PSR-3000 via USB-MIDI with the data of one specific channel of the MIDI file. For this purpose, a user-defined MIDI template would have to be created in order to control the relevant keyboard part (e.g. Right 1) via the Receive Port USB2. The Voice settings of the relevant MIDI file Channel would be transferred to this keyboard part in this way.
Hope this helps!
Best regards,
Chris