It is shown when the document is in edit mode. Setting constraints symbol="$" doesn't help.
<xe:djCurrencyTextBox id="budget" value="#{document1.budget}" defaultValue="0">
<xe:this.constraints>
<xe:djNumberConstraints
currency="USD" type="currency" fractional="false">
</xe:djNumberConstraints>
</xe:this.constraints>
<xp:this.converter>
<xp:convertNumber></xp:convertNumber>
</xp:this.converter>
</xe:djCurrencyTextBox>

Add parameter
showReadonlyAsDisabled="true"to your djCurrencyTextBox control:It will show your currency value with "$" symbol in read mode.