You can enter the time that you have spent on a particular task when your administrator has enabled the relevant setting. See the Task Time Entry Mode setting. If you are required to enter time against project tasks, we recommend that you enter your time on a daily basis.
Depending on the configuration of your org, when you click Copy From Previous Week, you might be able to select checkboxes to copy tasks and task hours. This speeds up time entry.
For more information, see the related tasks and reference topics.