This sometimes happens when you view or buy an item from an American seller, then everything is shown in US $$'s.
You need to log out completely, even shut your device down. Start up, and log into your homesite, https://www.ebay.co.uk and everything will be back in Sterling Pounds.
If it doesn't switch back, just refresh your page a few times, that will kick start it into showing the correct currency.
You need to ensure in your Site Preferences, link below, you have selected only postage to the UK.
https://www.ebay.co.uk/ship/prf
@chbee_3496
