You could try the course upload feature: https://docs.moodle.org/310/en/Upload_courses
I haven't done this but I expect that if you use this to update courses you can can specify a new category to place the courses into.
However, it may not be necessary - if you move a parent category 'under' another category I would expect all its sub categories and courses to move also. So you may only have to do it a few times in the course and category management that Colin mentioned.
I haven't done this but I expect that if you use this to update courses you can can specify a new category to place the courses into.
However, it may not be necessary - if you move a parent category 'under' another category I would expect all its sub categories and courses to move also. So you may only have to do it a few times in the course and category management that Colin mentioned.