You have to be an account Owner or Admin to be able to manage your account. First, go to the profile settings and update your user name and name, as wel as your account (company) details. Ensure you update these correctly and make them recognizable for your colleagues, as this data will be shown when you invite new users. Learn more about profile settings here: 

Once you have updated your profile settings, go to team settings and adjust the settings to your company's requirements.
NOTICE you can only select the team settings when you are in the team workspace! Read more about the team settings here.