Thanks a lot for the information! It works great for manually changing grades for homework problems.
But it seems that this does not work for gateway test/quiz problems here (V2.7). The 'status' is 0 for each problem (even if the grades for some problems are not 0). When we change a 0 to 1 the grade does not change. Any ideas on how to manually changing an individual grade for a gateway test/quiz problem? Any suggestions would be appreciated.
For gateway/quiz sets the status of the problems is slightly more complicated: there is a set (e.g., "quiz01") that is assigned to every student, but it's essentially a template for the set that they actually work. The latter will have ",vN" appended for the Nth version of the quiz that is taken. If the quiz is only given once, there will be only one of these.
The result of this is that changing the status of the "quiz01" set doesn't change how the student seems to have done on the assignment—that is governed by the status of the problems on the "quiz01,v1" set. You can edit that as well, but it requires some finding because it isn't a set that appears in the list on the instructor tools or homework sets editor pages.
To update a version of a gateway/quiz for a student, you want to edit all sets assigned to the student (Instructor Tools -> View/edit all sets for one user). That will give a list of sets including the versions of the set that the student has taken, and clicking on the version name ("quiz01,v1") will allow editing anything about it, including the status of the problems.
(This is described on the Gateway/Quiz wiki page, Gateway Tests and Quizzes.)