The first thing I'd suggest, while logged into your account here, is to set a PIN for pass purchases. Click on the little man in the top right, manage account, PIN. There are instructions there on how to set a 4 digit PIN code.
Secondly, under manage account, go to devices and see if there are any devices you don't recognise. If there are, delete them and then head to the section for passwords and request a new account password.
Even if there aren't any unknown devices, you may want to request a new password.
As an added later of security, you may also want to consider changing your routers password.
Obviously, changing passwords will mean logging into all the devices with both the new account password and router password.