Having a vertical
scrollbar displayed seems to indicate that you have two rows of icons in your Taskbar. Try changing that to a single
row of icons.
If that doesn't work, you might also try resizing your Taskbar: Right-click an empty area on the Taskbar. UNlock it by clicking ‘Lock the taskbar’ to remove the check mark. Bring your cursor to the edge of the Taskbar until the cursor changes into a double-headed arrow ⬍ and then drag the border away from the edge of your screen, until it is the size you wish.
Also, you can take a look at these tutorials to help you resize your Taskbar: 'Resize the Taskbar' video (video from Microsoft) Windows 7 Taskbar Tweaker : Tweak Windows 7 Taskbar Button & Thumbnail Preview sizes | The Windows Club