SQL XML .Modify syntax - sql-server

Question

I'm trying to figure out what wrong with my XML update query. I don't have much experience working with XML in SQL but I thought this should work.
I want to update a value of the PATH value in XML.
Here's what I am currently trying:
DECLARE #PATH VARCHAR(500) = 'TEST'
IF OBJECT_ID('tempdb..#SUBSCRIPTION', 'U') IS NOT NULL
DROP TABLE #SUBSCRIPTION;
CREATE TABLE #SUBSCRIPTION (ExtensionSettings xml)
INSERT #SUBSCRIPTION
( ExtensionSettings )
SELECT '<ParameterValues><ParameterValue><Name>PATH</Name><Value>\\valinor\group\XFER</Value></ParameterValue><ParameterValue><Name>FILENAME</Name><Value>REPORT CARD TEST - SITE - YYYYMMDD</Value></ParameterValue><ParameterValue><Name>FILEEXTN</Name><Value>True</Value></ParameterValue><ParameterValue><Name>RENDER_FORMAT</Name><Value>PDF</Value></ParameterValue><ParameterValue><Name>WRITEMODE</Name><Value>Overwrite</Value></ParameterValue></ParameterValues>'
SELECT LEN(CAST(ExtensionSettings AS varchar(8000))) DL_XML, CAST(ExtensionSettings AS varchar(8000)) EXT_XML
FROM #SUBSCRIPTION
-- UPDATE ATTRIBUTE
UPDATE #SUBSCRIPTION
SET ExtensionSettings.modify('replace value of (/ParameterValues/ParameterValue/#Name[.="PATH"])[1] with sql:variable("#PATH")')
SELECT LEN(CAST(ExtensionSettings AS varchar(8000))) DL_XML, CAST(ExtensionSettings AS varchar(8000)) EXT_XML
FROM #SUBSCRIPTION
SQL Server says 1 row affected but nothing changes.
I need to update other columns too but assume once I get this working the others will work the same way.
Can you help me and point out what I am doing incorrectly? I am trying to automate some SSRS file share subscriptions but the only examples I find are for e-mail and they edit the XML data as text.
Below is the XML I'm working with in a readable format:
<ParameterValues>
<ParameterValue>
<Name>PATH</Name>
<Value>\\valinor\group\XFER</Value>
</ParameterValue>
<ParameterValue>
<Name>FILENAME</Name>
<Value>REPORT CARD TEST - SITE - YYYYMMDD</Value>
</ParameterValue>
<ParameterValue>
<Name>FILEEXTN</Name>
<Value>True</Value>
</ParameterValue>
<ParameterValue>
<Name>RENDER_FORMAT</Name>
<Value>PDF</Value>
</ParameterValue>
<ParameterValue>
<Name>WRITEMODE</Name>
<Value>Overwrite</Value>
</ParameterValue>
</ParameterValues>

Answer 1

After a couple of hours of trial and error, I have figured out the syntax to update the value of one element based on the value of another element in the same node^. I wasn't able to find a similar example.
-- UPDATE PATH ATTRIBUTE
UPDATE #SUBSCRIPTION
SET ExtensionSettings.modify('replace value of (/ParameterValues/ParameterValue[Name="PATH"]/Value/text())[1] with sql:variable("#PATH")')
-- UPDATE FILENAME ATTRIBUTE
UPDATE #SUBSCRIPTION
SET ExtensionSettings.modify('replace value of (/ParameterValues/ParameterValue[Name="FILENAME"]/Value/text())[1] with sql:variable("#FILENAME")')
Before:
<ParameterValues>
<ParameterValue><Name>PATH</Name><Value>\\valinor\group\XFER</Value></ParameterValue>
<ParameterValue><Name>FILENAME</Name><Value>REPORT CARD TEST - YYYMMDD</Value></ParameterValue>
<ParameterValue><Name>FILEEXTN</Name><Value>True</Value></ParameterValue>
<ParameterValue><Name>RENDER_FORMAT</Name><Value>PDF</Value></ParameterValue>
<ParameterValue><Name>WRITEMODE</Name><Value>Overwrite</Value></ParameterValue>
</ParameterValues>
After:
<ParameterValues>
<ParameterValue><Name>PATH</Name><Value>\\valinor\group\XFER\TEST\Site1</Value></ParameterValue>
<ParameterValue><Name>FILENAME</Name><Value>0123456X - 20180615</Value></ParameterValue>
<ParameterValue><Name>FILEEXTN</Name><Value>True</Value></ParameterValue
<ParameterValue><Name>RENDER_FORMAT</Name><Value>PDF</Value></ParameterValue>
<ParameterValue><Name>WRITEMODE</Name><Value>Overwrite</Value></ParameterValue>
</ParameterValues>
Now if I could just figure out how to combine these into one statement. But close enough for now.
^Please feel free to correct any incorrect wording.