To change the password for yourself or one of your store's other administrators, go to to Account -> Admin Users. You will then see a list of all of the users for your store. Select the one you would like to change the password for and click the "Edit" icon. If you have not already done so, you will need to enter the user's first and last name. After that, just enter in the new password you would like to use and confirm it in the box below. Click save and you're done!
*Please note that the Multiple users feature is only available with a business plan.