Do you want to be able to expand your entire tree structure or find a particular component?
If in Tools/Options/FeatureManager, you check the option "Scroll down the object of the selected tree in the view", as its name suggests, when you click on a part of the 3D, the tree unfolds by itself to point to the selected component.
If you want to find a component by name, property,... ,you can also use the text box filter at the top of the Feature Manager, under the tabs.
In fact, it's to find out on which components some sketches have remained apparent...
So by clicking on a sketch line in the assembly, SW unwinds the FeatureManager to the component.
But sometimes, even having a sketch and clicking on it, sw doesn't unroll the tree. And the same in the room alone. And it becomes painful to look for it, I open the functions one by one...
If, on the other hand, you haven't renamed your sketches, in the filter at the top of the Feature Manager, start typing "sketch" and your Feature will unfold by itself, showing all the sketches! From there you will be able to see which ones are shown.
To hide the sketches that have remained visible, a trick by using the filter of the selection tree, write "esq" in it, and you can directly see which sketches are shown or hidden:
To expand an entire tree, simply select the root of the tree (part or assembly) and press the * key on the numeric keypad (the other key near "Enter" has no effect).
The reverse of this command is indeed shift+c
The Expand/Gather Tree shortcut is only useful when the tree appears in the graphical view (when a command is run for example). It is of no use in the case you describe.
Otherwise, the display filters of the tree or the graphical view that have been described in previous posts are also good ways to find information or to quickly hide all sketches in a document.
In SW 2016, you'll have a new "weapon" at your disposal to find out which part or function a sketch belongs to: thebreadcrumb thread. I'll let you watch the description of this new tool and this video (Increase your productivity) which describes this evolution, among other things.