Time Taken To View A Form

I'm attempting to create a short questionnaire. I have 1 table with 5 multiple choice questions, each one to be answered singly through a form.

My problem is I would like to know how long each participant takes to answer each question, therefore I am trying to save the time (StartTime) from when a form is opened to the time (EndTime) when the next question button is pressed and then again for the following form/question etc.

I have tried to do this through the use of Macros on the Form using the Set Value Action to populate the value/time in the Table - without any success - it does not like using the Time () command through a Form! why??

How can I get the above to work?

If there is no easy way to do this I would like a counter to start when the first Form is open and finish (wherever Form may be open) after 90 seconds (e.g. a user has 90 seconds to go through as many questions/forms as possible) before the questionnaire closes and goes back to the first form.

Any advice would be gratefully accepted.

Thank you for your time.