There are small arrows indicating the column and order (up/down) by which entries are sorted in dashboard widgets tables. The sorting works a little bit different in different tables.

Widgets like 'Problems' and 'Action logs' allow to specify the column and order by which data is sorted (field 'Sort entries by' in configuration window). On the other hand, most widgets (e.g. Web monitoring, Host status, System status) doesn't have such field and user can only see by arrow indicator at the header of table which column is used;

The Plain text widget do not have such arrow at all.

Arrows are not clickable which is confusing.