You can control how your report results are sorted in the report editor.
The default sort order is alphabetical or in the case of time-series reports, chronological, but you can also sort results by any metric in your report.
Click the pencil icon in the top right of any report to open the report editor:
Scroll to the bottom of the report editor to where you will find the 'Sort by' section:
Here you can choose the default sort or pick a metric to sort by.
Make your choice and hit the 'Preview' button:
If you are happy with the resulting report his 'Save Report' - otherwise 'Discard Changes'