I'm not sure I understand, what exactly do you mean?

Oh ok, I get it now. So how do I change my country/rejoin in the Microsoft store app. I think the Microsoft store app is still the USD store instead of the CAD store.

This could be a bit complicated now.

What region do you have setup as in your system? It can be checked at settings/time and language/region ? This will be the region that store uses in your windows 10 device.

Do note that if you make changes to it and you have previously bought apps and games from that region it could cause issues if you change the region.

To keep it short the best practice is to make sure you have correct region in your windows and use the currency only for that region.

Region and everything is correct, the money is in my balance. But what I don’t get it that when I try to make a purchase on the Microsoft store app, it should’ve let me use my Microsoft store balance as an option to pay. But instead, all it does it ask for my card.

login here with your account :

It says “5 dollars CAD”.

That is good. Something else that can be causing issue is that you are trying to buy something that is more than the account balance (remember you will need to account for the taxes too so if you have 5$ CAD and are in Canadian region store but if you try to buy something that is 4.99 you wont get the balance option since taxes inclusion will bring the price over what balance you have)

Apart from this you cannot buy recurring subscriptions (those which are paid month to month via a card) with your balance or pay for an overdue subscription (these will require a card payment or paypal balance)

Oh, ok I get it now. But what I don't get is that when I try to purchase a $0.99 one-time purchase item, it still doesn't show the option to use the card. The total along with taxes should be less than $5 but the option still doesn't show.
*I don't have any cards as a way to pay, could that be the problem?