You are using the win7 system, you must have found the "super taskbar" a variety of new features, to help us work or study life more convenient and quick. In the Win7 taskbar, the running program has a thumbnail preview label, and the same type of program merges together, saving the space occupied by the taskbar. If you're not used to this form of merging, you can split them up into a win XP mode.
Merge display of programs in the taskbar
Click the right mouse button in the blank space of the taskbar and select the last item "Properties".
Select "Properties"
In the Open Properties dialog box, select the Taskbar tab, and in the taskbar buttons area, there is a drop-down menu that appears as always merge, hide labels, select Never merge, and click Apply. Now let's see if your taskbar display is changing. Find out what Windows XP feels like once familiar.
"Never merge" helps you take apart the merge procedure
If you think the display is too crowded after the change, you can also select "merge when the taskbar is full" so that when you open the program too much in the taskbar, the label will automatically merge again.
Change the display after setting