To assign a Mark, Issue, or Comment to a single document at a time use the Work Product Inspector on the Review menu. Open the Work Inspector dialog box to check/uncheck the appropriate Mark, Issue(s), or add a Comment. Once a document has been given a privileged type mark, the Privilege Basis drop down menu becomes active and available.
The Propagate comment to duplicates (will overwrite) check box at the bottom of the Work Product Inspector (see above) refers to the information added in the "Add comment here" box only and does not impact the Mark or Issue Code(s) applied.
Note: Documents can have only one Mark but may have multiple Issues. Comments are automatically saved.