By default, Outlook highlights the word(s) you search for in yellow. This can be difficult to see as it does not stand out very well. To make your keywords really stand out, change the highlight color to something that is more easily seen. To do this:
1. Click Tools, mouseover Instant Search and select Search Options.
2. In the Search section, make sure that the Highlight the words that I search for checkbox is checked.
3. Next to Highlight color, click the Change button.
4. Select the desired highlight color and click OK.
5. Click OK to close the Search Options window.