thumbnail rescann - how?

[RainerG]

how can i rescann the thumbnails, after setting another size in preferences (before 300, after 250 :-)?

[Mario]

Select the files you want to update, then choose <Shift>+<Ctrl>+<F5>. Or use the Rescan command from the context menu and hold down <Ctrl> to get the advanced options.

For details: Search for Rescan in the Help Index, then click on Folder Rescan.