Replacing Online File with New MuseScore 4 Soundfonts

Hi all,

The title says it all really. I am trying to replace a score already online with an updated version that has the nice new fancy soundfonts.

My usual way is to log in online, click on the relevant score, go to the three dots on the right hand side, and from here replace the old version with the new one. This however only uploads the engraving and the playback online is with the default "MuseScore basic" soundfonts.
I have tried opening Musescore 4 and using to the "Publish to Musescore.com" under the "File" tab and checking the box to upload as MP3 so as to enable the new soundfonts, but this uploads it as a brand new score (albeit with the new sounds in playback).

I can't see any obvious way of updating an old score online with the new soundfonts without creating a brand new score online. There must be a way of doing this, but I can't work it out.

What am I doing wrong here?

Thanks in advance,
Dave.