Forms :: Check Box In A Form Which Shows Data From A Table In Tabular Layout

I have made an unbound check box, named "myckeck" in a form which shows data from a table in tabular layout.

1- When I check one check box, all check boxes are checked. How can I solve that? I mean I want to check or clear check boxes independently.

2- I made a text box, named "jobdate" to sow todays date automatically upon checking a check box.

Code:
Private sub mycheck_afterupdate()
jobdate = date
End

But this is not working and checking a check box does not make anything to happen.

3- Then I made this expression in the default value of "jobdate" properties:

iif( mycheck = true, date(), null)

This not working either.