Most users do not want to see all columns in grid and also wants to preserver width of columns as they want whenever they use File renamer. Now with File renamer, you can select columns you want to see in grid area and width of the column in grid area; after that program will remember that width and columns setting whenever you open File renamer. It's small but very important feature for frequent users of File renamer.
To see selected columns you want to see in File grid you just need to check the check box of that respected column. Only selected Column will be visible in File grid.
You need to check the check box 'Apply last grid Column Width' to preserve width of columns as you have set in file grid. By default it's checked.
You need to check option "Allow numeric sorting in filename" to allow only numeric sorting in file name column. By default it's unchecked.