I Can Not Arrange Safari Bookmarks Folder

There are 2 folders in Safari as Bookmarks Folder.

A) Favorites

B) Others

I save YouTube page to Favorites folder.

It can’t be saved into Favorites folder for some reason 

Although Favorites folder is checked whilst saving.

That’s ok.

Then go to the Safari side panel.

I can not drag and drop Youtube page into Favorites folder. 

When I click It goes to rename mode.

I copy It then right click to favorites folder. There is no Paste option on the Favorites folder.