You can click on the Top Level folder and have all images displayed that are in the subfolder under it.
For that to happen you have to click the Plus sign at the top of the Folders section and select Show Photos in Subfolder.
Sorry there is nothing like that in the Collections section.
I create a lot of folder and dynamic collections and I would like to open all folder In one way and not click all left arrow to. Is there a way to open all folder with a keyboard shortcut?
To clarify, your screenshot shows that what you called "folder" is a "collection set" in English. What you called "dynamic collections" is a "smart collection" in English.
You can expand all the nested collection sets by holding down Alt (Windows) or Opt (Mac) when you click on the arrow:
Holding down Alt/Opt when you click again will collapse all collection sets.
You can see a complete list of keyboard shortcuts (many of which aren't in Adobe's Help) here: http://www.lightroomqueen.com/keyboard-shortcuts/lrcc6/
Thank you very much its perfect !
it allow my Mac to work with more speed !
and yes, im gonna take a look at the keywords shorcuts,
thank you John !