Your password is the key to all your personally created contents; email, documents, images and assessment tasks. When someone else knows your password they can see them all. If they have access to your email they can send messages that appear to come from you.
Your password needs to be private - do not share your password with friends. Email them content or use the sharing option to grant them access to only the items you want them to see.
Your school username and password should never be used for any other website or app unless that app is using the school login system (often called SingleSignOn or SSO).
Your password needs to be strong - if it is still 4 to 8 characters long it's is too easy to guess. Instead use a passphrase.