In order for you to change your Company's currency you just have to follow the steps below.
On the top right hand of your dashboard, you will see an icon with a silhouetted face (or your own picture if you have changed it) with an arrow pointing down next to it.
Upon clicking on the arrow, a drop down list will appear with the options Profile, Upgrade your plan, and Settings.
Click on the Profile Option.
On the left hand side on the screen, you will see four sections:
1) My Settings
Click on the word Profile underneath the Company heading.
Change the existing currency of the Company by clicking on the box below the "Currency" heading and selecting the currency you wish to replace. Click "Save Profile", in order for the changes to be saved.
Your Company's currency is now changed.