Use of short key in Section C

Dear Sir,
For Section C, can I use short key such as Ctrl C, Ctrl V ?
Although as in the instruction of ACCAC website, we are allowed, but in the real exam, the supervisor request the candidate not to use these short keys to avoid of hanging up computer
Actually, there is some cases candidate’s computer has been hang and they must do the exam again ( in 3 next hour)
The supervisor said that the use of short key is the reason
When hearing that, I do not dare to use short key ( although trying 1 time only).It makes the speed of completing the exam slower.
Please give me an advise for this issue. I would like to use short key but do not want to have any problem for exam.
Thank you