Qgis gives so many style options that sometimes is difficult to restore last settings after playing with properties dialog.
I made a plugin to undo/redo properties changes aimed to recover last layer state.
The plugin load a little toolbar whith undo and redo icons :
when a change is applied to layer the toolbar changes undo icon highlights and allow to recover last state:
If undo performed redo icon highligths and allow to recover undone state.
quick video tutorial on youtube.