Yes, we can change the default period of 30 days in grids, by changing the Default days field value in Click2Undo Configuration record.
Yes, we can change the number of rows in the History and Restore Deleted grid. The number of rows in History and Restore deleted grids are based on the 'Records Per page' set in User’s personal settings.
So in order to change it, you need to Click on gear icon at top right corner then click on Personal Settings.
Then change the 'Records Per page' value and click on OK.