When you launched Bee for the first time, you were presented with the New Project window. Selecting a Project type would have taken you to a screen where you could enter your account details.

If you change your password on your server, you can update the credentials Bee uses by going to Preferences (Bee > Preferences) and then the Accounts tab.

From there, you can double-click the relevant account to update its password or any other details which you initially entered.