If you're hosting an event and wish to display ticket prices in a currency other than the default USD at checkout, here are straightforward steps to guide you.
Head to Event Setup > Settings > Billing & Tax Settings.
Click on the dropdown menu under Payment Currency.
Scroll to find your currency of choice, or type it in.
Once you've selected it, press Save.
The currency shown on your event site at registration should be updated straight away.
Keep in mind that for your event, you can only display tickets in one currency simultaneously. This means you can't show one ticket in GBP and another in USD, for example.
These settings are event-level, so if you have multiple events and want them all to be in a currency different from USD, you'll have to do this for each event.