If you work on the same Project, Task, every time, then you can enter only the hours worked using the Weekly tab in Salesforce.
To enter hours,
- Go to the Multiline Time Entry screen, click the Weekly sub-tab
- You see the current week time details if any,
- Click the "Copy from prev week" string to copy Projects, tasks, and hours from the previous week,
- Edit the time details if required, and click the Submit button to save the time details.
Note: By default, the start time is considered as 12.00 a.m. if you enter time from the Weekly tab.
If you want the start time to default to any other time, please let the Salesforce administrator know and they can change it.