Comma format for a number from a measure

Hi,

I cannot find where to add commas to a number in a report to separate the thousands.

I think that this must have moved position as I previously did this, but missed one measure.

previous answers say its in Modelling, I can't see it there or in the Format Tab.

Where is this now please? 

I need the 18089 to look the same as the 27,054 below.

Thanks