I notice there are some numbering on the tab of each new query (such as the number 52, 56, 57 and 58 as shown in the following pictures)
What does these numbers means and is it possible to reset to the first original values?
The numbers represent the process id of the session associated with that tab - as every time you open a new tab it opens a new connection to SQL Server for you. They are not necessarily sequential but they can be. If you run the following command you should be able to see an entry for each of the tabs/connections that you have open:
I hope this helps you.