Double Click, this one takes some practice you will have to click the Tab twice at the correct speed.
Right Mouse Click, this is an easier way to accomplish the task. One right Mouse click on the Tab that you wish to rename.
Let us practice renaming the Tabs. Make sure that Sheet1 is the Active Tab, I know that it is Active because it is white in color and has no line dividing it from the Spreadsheet. Let’s name it Phonebook; you can try either way to rename the Tab that you want, Double Click or Right Mouse Click. Once you have renamed it either move the cursor to somewhere on the Spreadsheet and Left Mouse Click or hit the Enter Key and this will finish the Rename process.
Now let us click to Sheet2, and you will rename this to Address Book.
That is all there is to it, of course you can change the names to whatever you desire.