Explorer not full screen

If i want to open an Explorer Window, I see the small Bar under the Explorer icon at the task Bar. And when i place the Mouse over the icon, i See the small Window but never See the Explorer in full screen.
All Updates are made and i have resettet what could be resettet.
Sorry for My "english" and thanks for Your hints.

Audioteufel

Are you clicking on that icon or just placing the mouse over the icon?
Can you press WIN+E and see if that works?

WIN is the key on the keyboard with the Windows logo.

To add, the icons in the upper right corner of a window have Minimize, Close and Maximize/Restore. The Full Screen is different, a separate feature, and usually reached by pressing F11 or on Notebooks maybe Fn + the F11 key, fills the screen and removes some Toolbars when used, gives more visual room for what is open/in focus.

Win + E works, alt +Tab Shows all opened Explorer Windows, but never full screen

Full Screen F11 works fine on my Notebook as I described before. But with "all opened Explorer Windows" it only works with the one in focus/in the forefront.