If you need to change the currency settings on an existing event or project, you have two options. First, you can view the projects on your planner dashboard and click EDIT SETTINGS under the relevant project. Second, from within the project you can click SETTINGS on the top right of the tool bar. Either option will bring you to the same PROJECT DETAILS menu where you can scroll down to PREFERENCES and choose your currency for that project or event. Updating your currency here will not affect other projects.
While this will change the currency symbol for a specific project, if you need to update the currency default for your account, return to your planner dashboard and click BUSINESS SETTINGS, then choose your default currency from the drop down menu. This will set the currency preference for all new projects that you create moving forward.