This is an xml file for one of my frames and shows what I had and what I changed it to. It should help you see what you need to change.
Lua Code:
<Frame name = "XMP_BackdropTemplate" inherits = "BackdropTemplate" virtual = "true">
vvvvv New Code
<KeyValues>
<KeyValue key="backdropInfo" value="BACKDROP_TOOLTIP_16_16_5555" type="global"/>
<KeyValue key="backdropColor" value="BLACK" type="global"/>
<KeyValue key="backdropBorderColor" value="WHITE" type="global"/>
</KeyValues>
^^^^
vvvv Old Code
<!--Backdrop
bgFile="Interface\Tooltips\UI-Tooltip-Background.png"
edgeFile="Interface\Tooltips\UI-Tooltip-Border.png"
tile="true" >
<EdgeSize val="12"/>
<TileSize val="16"/>
<BackgroundInsets left="5" right="5" top="5" bottom="5"/>
<Color r = "1" g = "1" b = "0" a = "1" />
<BorderColor r = "0" g = "1" b = "1" a = "1" />
</Backdrop-->>
^^^^
</Frame>
And this file shows you the presets available and how you can create your own if none of them suit your needs.
https://www.townlong-yak.com/framexml/live/Backdrop.lua