Helix and US app store

I have a US iPhone 11. We just had Helix installed in Montreal but I can’t load the Helix app on my phone, apparently because it defaults to the US site; it can’t even find the app. I can’t seem to change this. I have loaded other Canadian apps on my US iPhone with no problem. The phone will not let me switch to the Cdn store as it say I have other US apps that require it to stay on US store.