If you're referring to Phasma, then as a general rule of thumb you should ignore her military rank. According to SW literature, although she's technically a captain, her true position in the First Order is much higher (more or less on the same level as Hux & Klyo Ren).
***EDITORS*** All the Star Trek Discovery Season 0 ("Short Treks") episodes here are MISNUMBERED. According to IMDb, s0e01 is Runaway, s0e02 is Calypso, s0e03 is the just-released Brightest Star; s0e04 won't be out until Jan. The links HERE for "01" are correct, but are the same as for "02" (or mostly so?--I didn't look at all of them), "03" are for the real 02, and "04" are for the real 03. Some other sites are making the same mistakes.
Watch The Last Ship Online
Their mission is simple: Find a cure. Stop the virus. Save the world. When a global pandemic wipes out eighty percent of the planet's population, the crew of a lone naval destroyer must find a way to pull humanity from the brink of extinction. Executive Producer Michael Bay presents The Last Ship, starring Eric Dane, Rhona Mitra and Adam Baldwin.