Being able to access the agendas of other users in Teamleader is a setting. This can be edited under Settings > HR > Users.
In the overview of your users you can click on the pencil next to the one you want to edit and go to "Agenda" in the second column. If this user does not have admin rights, you will see a dropdown menu where you can choose to which agenda he/she should have access to.
There are three options:
- Own calendar only
- Entire team calendar (only useful in case you want to work with teams)
- All calendars
Therefore, if you can't see the agenda of other users it means that the admin user of your account has given you a limited access to other agendas.