longer em dashes?

Hi, as I write my novel, I notice that two dashes turn into a bigger—yet still small— em dash. If they were the same size as the one here in the forum that I just created in the line above, I would be very happy, but creating them in Scrivener, even using alt+0151 makes them super small. Any ways I can fix this?

Probably depends on the font you are using.

Mark