Hello José,
You already have only single component, thus there's nothing to merge.
In some cases the alignment may be split into two or more components (Component 1, Component 2 and etc), then you could switch between them by double-clicking on the component's label in the Workspace pane and merge, if necessary.
For the testing purposes, you can right-click on one of the higher level parts and choose "Split Component" option to get two components in the Workspace and see, how it generally works.