You can set an assessment up to pull a random selection of questions from any question set.
1. Click Manage > Assessments.
2. Click the questions (pencil) icon next to the assessment you would like to edit.
(*If you are creating a new assessment, click New Assessment.)
(*If you selected New Assessment in the step above, you'll need to navigate to the "Questions" tab)
3. Click the actions button in the assessment section, OR the "+" symbol on the left to import questions.
4. From there, follow the prompts to insert questions from existing assessments.
(*Note the option to select all of the question from a particular Assessment Section)
5. From the Actions menu, you can also decide how many questions should be randomly shown to students taking the assessment.
This video about Assessment Section Settings may also be helpful: