When I create a task, it shows only one set of descriptors, but the task is for students at different phases.
In your gradebook, we can only show one set of descriptors. However, the descriptors shown to students and parents are based on the student’s phase. You can verify this by checking each individual student profile.

For example, in this screenshot Crispin received a 7 on Criterion A for the task Chinese Introductions. Crispin is taking the class at Phase 4.

Language Acquisition MYP descriptors2

Max received a 7 on Criterion A for the same task, but you can see his descriptors are different because he is a Phase 3 student.

Language Acquisition MYP descriptors

How does this all look on report cards?
Same idea — we show the phase-specific information for each student. In the screenshot below, we automatically adjust the title of the class so that only Phase 3 shows, and the descriptors are all for Phase 3. (It’s Max’s report card.) Crispin’s report card would show Phase 4, and so on with the other students at different phases.