To lock the Design mode

Once aspects of the document that require input or that permit modification have been designated, you can restrict access to the Design Mode to ensure these specifications are not altered in any way. Locking access to the Design Mode prescribes that entry to this mode is only permitted by the use of a password.

While in the Design Mode, on the Tools menu, select Lock Design Mode.
Enter a password twice (the second time is for confirmation purposes).
Click OK.

With a password intact, access to the Design Mode requires identification of this password.

Note

Once aspects of the document that require input or that permit modification have been designated, you may wish to restrict access to the Design Mode to ensure these specifications are not altered in any way.
Once the Design Mode is locked, the button to switch between modes will switch the user between Form Mode and Form Mode with editing enabled only.