ontime macro button activates all sheets in woorkbook intead of just the one it is pressed

Hi

Please see example wb

I have a command button on all sheets (only 2 on the test but will have 31)
My problem is that when i press ths start time button it starts the time ok but if i go to another sheet the time will start automatically on these sheets
even on the data sheet which does the macros head in!!!!!

How can i name each sheet or button to only make them work if they are pressed so other sheets could be viewed without the clock starting??
There are other cells/codes looking at the time cell to use a count down etc

Thanks for any help on this

Peter