LHi,
The quick answer is, you don't. The reports do have some flexibility but
formatting is not one of them, generally. However, depending on which
report you are interested in, there are other ways to get the equivalent
information in a form that you can format. In many cases, customizing
one of the Project views (e.g. Gantt, Resource Usage, Task Usage, etc.)
will give a quick solution that is acceptable or at least close enough.
However if that just doesn't make it, then VBA can be used to export the
Project data to another app (e.g. Work, Excel, PowerPoint) where it can
be formatted however desired.
The bottom line is, I have yet to come across a report of Project data
that I could not get and format exactly as needed.
Hope this helps.
John