When opening the widget, the default column widths might be too narrow to display all of their content. You can manually resize a single column, or you can change the width of all columns in the widget to show all of the values.
To resize all column widths to fit the data:
Right-click on any column heading to display the column heading context menu.
Select Fit all columns to content.
All of the column widths in the widget change to fit the widest value in their respective columns. Some of the right-most columns might no longer be visible, but you an resize the widget manually, as desired.