Teachers can create test questions in the “Question bank”:

• Create
• Edit
• View
• Organize and delete questions in question categories.

Questions in question categories can be made available system-wide, within a course or within a test.
Teachers have access to the question bank:

• Either via the course navigation on the course page: Click on “Question bank”
• Or via the activity navigation on the test page: Click on Question bank

More information about Question bank on Moodle.org.