You've completely reversed your scenario!
In Post #1 you say "...I want to like this: (if) ID=1 record Button1 must be enabled=True...."
Then, in Post #5 you write "...When I push the ID1 line button, ONLY that "a1 text box" must be enable.(Not ID2 a1 text box)..."
Which is it? Are you trying to Enable the Textbox or the Command Button?
If it's the Command Button, on a Continuous Form, you can't have it Enabled on Record and not on all Records...that's just the way Continuous Forms work. While you see multiple Buttons, only one Button Control actually exists.
You'd have to use a Textbox in place of the Command Button, tweak its Formatting to look like a Command Button, then use Conditional Formatting (off of the Menu or Ribbon) to Enable/Disable it.
Linq ;0)>
The problem with making anything foolproof...is that fools are so darn ingenious!
All posts/responses based on Access 2003/2007