@awilson , the easiest way to identify the correct exchange is to open TV's main page and use the search box.
Type the symbol you’re interested in, then from the list of matching tickers (for example, “SPY”, which appears on multiple exchanges), select the specific one you want.
On that line you’ll see two options: “Launch chart” and “See overview”. Choose “See overview”, and on the page that opens, check the end of the URL: it shows the exact exchange/symbol format to use (for example, AMEX-SPY).