Security is cited as the number one objection to Cloud for 49% of organizations (IDC 2017). Should you be concerned? The security investments made by the major Cloud providers is significant and has created cloud platforms in which security breaches, due to vendor error are rare. In fact, the Cloud has proven to be more secure than most non-cloud environments.
To start with every on-line account should have a separate and unique password. It should be at least 12 characters long with upper case, lower case, numbers and symbols. Do not make it a dictionary word. You are probably going to say how do I keep track of all these new passwords? The answer is a good password manager, there are many.