I'm evaluating CiviCRM for my organization and noticed something about the demo report tables that concerns me. Hopefully I'm just missing something. Do I have to create a new report or modify an existing one in order to change the sort order of a field? For example, I'd like to view the Contribution Details report and quickly sort it by amount, but when I click on the amount column header, nothing happens. Why can't I sort by amount by clicking on its column heading? Did CiviCRM used to have that capability but there was a bug that caused problems, so you took it out?
How a report is sorted is defined in the Report Criteria. Depending on what data the report looks at, you can sort of different criteria. It's usually called something like "Order by columns" and appears below the Selected Columns. Reports generally sort in date order.
If you want to play about with the data, the easiest thing to do is export to CSV and save in Excel so you can sort, filter and build graphical representation of your data as you wish.
Something I did once was to apply DataTables to the output of a CiviReport, adding the necessary JS in the template. That let me sort by whatever column. It was a bit of a hack though. Not a good idea if your report has an alterDisplay function (eg. to make a contact name into a link to that contact). I also had to override CiviReport's limit() function so DataTables would see all the rows. But now I understand CiviReport a bit better as to what I can put in the configuration array.