Selecting a Main Voice will automatically change the Dual Voice and the settings related to the Main Voice and Dual Voice, as well as some of the other settings-- Reverb Type, Chorus Type, Harmony Type, and Arpeggio Type and their related settings.
But the Split Voice and its related settings are not normally affected by changing the Main Voice.
The main exception to that rule is when you pick one of the "left arpeggio" voices-- on the PSR-E463 these are Voice Number 292 ("Finger Bass Left") through Voice Number 301 ("Strum Left").
Another possible exception is when you scroll through the voices, because there is at least one point where scrolling from one Voice Number to the next Voice Number will reset the Split Voice and its related settings back to their defaults.
I should add that the behavior described above is the way it works on most of the PSR-E models that I have, but it could vary from model to model. For example, on my YPT-400 (which is the same instrument as the PSR-E403 but marketed under a different model name) the Dual Voice and its related settings are not affected by changing the Main Voice. And looking over the Voice List for the PSR-E403, it can be seen that the PSR-E403/YPT-400 has no preset voices where the Dual function is turned on and a given combination of voices are layered together as the Main Voice and Dual Voice. So it appears to depend on what types of preset voices are programmed into a given model.
As far as the OTS Voice, I think it affects only the Main Voice.