You can manage your credentials and personal information from "Personal Settings" section which you can open by going to Settings > Personal Settings.
First item is profile picture. Click on "Update Profile Picture" to add or change your profile picture. Your profile picture will be displayed on the upper right corner and in Intercom conversations.
You can add / edit your first name and last name from this section.
If you'd like to change your password, then type in your current password and new password. Confirm your new password by typing in twice. Click "Save" to change your password and any other changes you've made in your profile.