How to Unmerge cells?

I do not know how but I have merged three cells, and that in a weird way, selecting the first one, selects all of them, [1]. Only the first one has Merge and Center Cells pressed, [1], when I follow the tutorials, [2], it almost unmerges them, [3], but the name of the first cell is still leaving the cell, [3]. But when I add the name to any of the rest two cells, the name resets and is good, [4], I am worrying this is messed up.
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I see, this is how it works, when cell does not have space, it takes space from the next cell for if the next cell is empty.