Click on the organization name at the bottom of the navigation panel, then click the Settings tab.
Go to the 'Permissions' tab.
Select visibility of billable hours and pay rates by adjusting the menu under 'WHO CAN VIEW/MANAGE PAY RATES AND AMOUNTS EARNED BY TEAM'.
You can also choose who may approve overtime, or set it to be approved automatically, by selecting the corresponding options. Note that Managers can only manage the requests of users within their groups.
The same algorithm works for approving the time that was manually added by users. There is also the option of automatic approval or manual approval by people with selected roles.