created new Tiddlers as markdown

[rocky-III]

Thanks for your nice tiddlywiki- kanban plugin...

Is there a way that new Tiddlers are created as text/markdown as default ?
I tried by editing

$:/plugins/BTC/Muuri-Kanban/ui/KanbanColumnTemplate

form

<$button class="tc-btn-invisible tc-board-column-action tc-add" style=<<get-styles>> tooltip="new item" aria-label="new item">
									<!--<$action-sendmessage $message="tm-new-tiddler"/>-->

to

<$button class="tc-btn-invisible tc-board-column-action tc-add" style=<<get-styles>> tooltip="new item" aria-label="new item">
									<!--<$action-sendmessage $message="tm-new-tiddler" type="text/markdown"/>-->

but that did not help.
What could i try next? Thanks