Someone assigned me a task,but i can not receive the notification

i was assigned a task ,but i can not receive the notification,
i have nothing about my task infomation unless i go to the to-do list,
what is wrong,do i miss some setup?

Go to Notification Settings and check if the “Assignment” checkbox has been checked.

thanks very much .
by the way ,is there any method to set this for all the users when i access as Administrator?

i tried the method, I used Administrator assign a task to another user—wangs, wangs does received the task,but wangs does not get an notification here:

any updates on this?