If you open CRM > Settings and can access only Email section, that means that you don't have access permissions to configure CRM settings.
How it works
Only administrators can configure CRM settings. By default, it's the account creator.
The administrator can assign admin permissions to any user by opening this user's profile > clicking Actions and selecting the corresponding option.
There is another way to grant access to the CRM settings sections to a user. Click CRM > Settings > Permissions > Access Permissions > select a role > click the pencil button to edit it.
Enable the User can edit settings option > click Save > assign this role to a user > click Save.
The user will get access to the CRM settings section.