change default text highlight color tool in Word 2013

Since my previous response, I had shut down the Surface Pro on which I have Office 2013 installed and I have not just restarted it and taken the following screen shot which shows the Highlighting Colour still set as Pink which is the colour that I had selected when performing my original test to see if the selection was retained by closing Word and then restarting it.

If you want to use a macro to apply shading to the selected text, the only command that you need is

Selection.Shading.BackgroundPatternColor = wdColorLightBlue

Or, if you want to use anyone of the 16 million odd colours that are available, use

Selection.Shading.BackgroundPatternColor = RGB(0,112,192) which is the same colour as wdColorLightBlue.

When you click on the More Colors...button in the shading colors dropdown, you will see:

The values for Red, Green and Blue range from 0 to 255

RGB(0,0,0) gives Black

and

RGB(255,255,255) gives White

In the Styles pane, an entry such as "Pattern: Clear (Accent 6)" does not represent an actual style but instead some direct formatting applied to text. Select the shaded text range and click the New Style  button. In the dialog box, type a style name and choose "Character" in the "Style type" box. In the "Style based on" box, choose "(underlying properties)."

You can easily apply the style to text if you assign a keyboard shortcut, which you can do if you click Format | Shortcut Key. When you are done, click OK to return to the Modify Style dialog box.

If you want to transfer your new style to the attached template, select "New documents based on this template" before clicking OK in the Create New Style dialog box.