Well you should visit Acca's website All necessary information is given on how to attempt the paper and use the CBE system effectively
https://www.accaglobal.com/gb/en/student/exam-support-resources/fundamentals-exams-study-resources/f7/session-cbe-introduction.html
Also go to study resources and practice attempting the CBE exams By CBE Specimen as well as Constructed Response area that will help a lot
Hone your skills of spreadsheet to do computations. it will save you valuable minutes.
