Content Assist (Auto Completion) - Not working in Mac

Hi, when I was trying to update the content assist character in preference, I removed the default character. After that, content assist is not working in Mac version.

Question:

What is the character I need to put in back to make it work? Or how to make all settings to default?

Can I update auto completion to Command + Space in mac version? If so, how to do it.

Hi, is ctrl+ space working?

try put these " ,."