Molly was telling us:
Molly nous racontait que :

This is how it works... Sorry, I do not think you can change that.

You can try ActiveX controls from the Controls Toolbar, but those can spawn
a whole new set of problems... I tend to stay away from those and put up
with the X. After all, this is a Word limitation, not a sign of incompetence
on the designer's part! As long as your users understand that, you are OK!
Alternatively, you can use userforms as opposed to in-line forms.

Just to make sure we are talking about the same thing, the type of form that
you are referring to is
called an in-line form, not a userform.  A userform is a custom dialog that
is usually called via a macro.

See the article "How to create a Userform" at:

http://word.mvps.org/FAQs/Userforms/CreateAUserForm.htm

For more information on in-line forms, see:

Please Fill Out This Form
Part 1: Create professional looking forms in Word
http://www.computorcompanion.com/LPMArticle.asp?ID=22

Part 2: Adding Automation to your Word forms.
http://www.computorcompanion.com/LPMArticle.asp?ID=46

Part 3: Learn more VBA (macros) to automate your forms.
http://www.computorcompanion.com/LPMArticle.asp?ID=119

Part 4: Use custom dialog boxes in your Word forms
http://www.computorcompanion.com/LPMArticle.asp?ID=127

Part 5: Connect your AutoForm to a database to save input time and keep
better records!
http://www.computorcompanion.com/LPMArticle.asp?ID=136

There are a number of ways to create and use clickable checkboxes in
documents / templates. Some require protected or locked forms, others do
not. Take a look at the Checkbox template available at
http://www.addbalance.com/word/download.htm#CheckboxAddIn for an exploration
of these.