XSLT transforming data using choose

I have an XML Document, I want to use XSLT to change the formatting of the data.

XML Values

<UniqueName>XXX</UniqueName>
<Parent>XYZ</Parent>
<Name>ABC</Name>

Anytime there is an XXX in Uniquename I want to change Uniquename value to 123

I tried the below however It seems to add another column to the XML rather than transforming the XXX to 123

 <th style="text-align:left">UniqueName</th>
 <th style="text-align:left">Parent</th>
 <th style="text-align:left">Name</th>

 </tr>
 <xsl:for-each select="units/row">
 <tr>


 <Review> 
 <td><xsl:value-of select="UniqueName"/></td> 
 <xsl:if test="UniqueName= 'XXX'"><text>123</text> 
 </xsl:if>  
 </Review> 

What do i need to change to get the values I want