Hi,
Changing your category of work can be done provided you are receiving not less than 7,250QR and you have to certify thru bank salary transfer for the last three months of your salary.
At the same time your sponsor must allow you to change your status. At any given time you can apply for this.
Not to mention you have to proved your education attainment like diploma/certificate and transcript certified by your embassy.
Hope i help you with this, good luck and be well