Thanks again. I had english (UK) above english Canada in browser settings (language) which is why PowerApps thought I was in UK. I changed the order, now i get $12,000 when i use Text(12000,"[$-en-US]$#,###.00")

This makes me think that this is not a good "feature" that PowerApps uses the Browser language selection to determine which region you are in. If I have a colleague that is set up with English UK as his primary language browser, then my Power App will show £12,000.00, which will be completely incorrect, as this is not even a converted currency. Also, if someone is in the UK they may want to display $.
I guess i am not understanding why anyone would want Text(12000,"[$-en-US]$#,###.00") to display in different currencies, depending on your language selected, since the currency is not even converted, so will display misleading information.
I will be sure to always use the full format that you provided.
Text(12000,"[$-en-US]$#,###.00", "en-US")
Regards
Dave