Can't add foreign currency

I've been trying to add a foreign currency for invoicing since I need to bill my American clients in $USD. This is the help article that I found: https://ca-kb.sage.com/portal/app/portlets/results/viewsolution.jsp?solutionid=220924450010555&hypermediatext=null

I'm trying to follow the steps but the option I'm supposed to look for does not seem to exist. I go to settings -> business settings and there is no "currency" heading, neither under "financial settings" nor anywhere else. (Screenshot attached.) I upgraded my subscription from "Start" to "Standard" because the website said that Standard allows a second currency. I can't find a setting to allow that anywhere in my business settings, and I don't have the option to change the default currency for my customers when editing them.

Help!