I cannot switch back to my currency

The app remembers your last choice of currency.

If you selected some currency previously using the drop-down currency list, the app will remember it, even if your location is different now.

You can trigger currency autodetection again with the option 'Autodetect currency':

Please note that the option may look different depending on your app configuration, as in the following screenshots:

If you don't have a drop-down list you can enable it for a moment to clear the previous selection. Alternatively, you can remove your cookies or use a different browser.