How to set user security function?已解决 悬赏10积分

Scenario:

I created 2 users - "A" & "B" in Zentao system.

But I found that task assigned to "A" can be changed by "B" e.g. click on the "start" button or type comments.

Is there any security setting can be set to avoid this happen?

I want to limit user to change their own task or Todo list.

Is there any solotuion on this?

Please help.

Thank you.