It’s not possible to choose a preferred display currency for your project.
By default, the currency your project will display and collect funds in is determined by the country of origin* you indicate when building your project. For example, if your banking and identity information are based in, say, Hong Kong, your project goal and reward costs will automatically be displayed in HKD. Once your project ends, the funds collected will be sent to you in HKD. If you’re in the UK, they’ll be in GBP, and so on.
Kickstarter does offer backers the option to set a preferred display currency when browsing projects. However, pledges will always be collected in the project’s native currency, not in a backer’s preferred display currency.
*For projects launching from Denmark, Norway, Sweden, Switzerland, and Poland, creators now have the option to choose whether to run their project in their country’s native currency, or in Euros.