Logitech G502 button Use?

I want to use the bottom button on the left side with the scope on the G502 for editing with Fortnite but I can't use it, it is simply not recognized, that is normally the DPI SHift button but I deactivated it but did not bring anything SOLUTION?

I myself have the same mouse and I suspect that you can't use this key as a hot key, because otherwise you could no longer set the dpi higher and lower and the whole key no longer serves its purpose.

With that you can't change the DPI but that is the DPI Shift button where you have to stay on it so it is faster?

Not faster but just as you set it