It sounds to me that there are employees set up as users on the company file, which is a great way to have them manage their own time sheet activity. I can see how having it so they can only see their personal entries would be useful for privacy or other concerns, however. I'm happy to go over this with you.
Depending on which version of the QuickBooks you're using, there are different ways you can set up users. For instance, when using QuickBooks Enterprise, there are even more options to fine-tune user access. That being said, there isn't currently an option to block users from seeing another's entries or activities in the company file. Here's our Community article that outlines user access in QuickBooks Desktop: QuickBooks Desktop Users and Restrictions
There may be time tracking apps that work with QuickBooks Desktop you can consider to help this situation. The Apps for QuickBooks Desktop page has a wide variety of apps that you can browse to see if something meets your needs. This page is home to apps that connect with both the Canadian and US version of QuickBooks Desktop, so it may be worth checking in with the app's developer to make sure it connects as you need it before committing to it.
I also invite you to share feedback about the user accesses in QuickBooks Desktop to help us learn what steps we can take to grow the program. It's as simple as clicking the Help menu and choosing Send Feedback Online.