Your profile says you're using version 3.5-367. Grab the latest dev build from here: https://dolphin-emu.org/download/ (4.0-5930 as of writing) and see if the right-click will allow you to run the Dolphin using Optimus.
Also, when running a game, see what the yellow text in the top left of the screen says. It should tell you what graphics card is being used.
Also, when running a game, see what the yellow text in the top left of the screen says. It should tell you what graphics card is being used.