To get your own custom Journal button, start by cloning the New Journal button.

Then create your own config tiddlers, eg:

• $:/config/myNewTiddler/Tags and ...
• $:/config/myNewTiddler/Title and ...
• $:/config/myNewTiddler/Text

Edit your custom button and "search and replace" the config tiddler names.

Change the following lines, near the end of the tiddler from

<$set name="journalTitleTemplate" value={{$:/config/NewJournal/Title}}>
<$set name="journalTags" value={{$:/config/NewJournal/Tags}}>
<$set name="journalText" value={{$:/config/NewJournal/Text}}>

to

<$set name="journalTitleTemplate" value={{$:/config/myNewTiddler/Title}}>
<$set name="journalTags" value={{$:/config/myNewTiddler/Tags}}>
<$set name="journalText" value={{$:/config/myNewTiddler/Text}}>

if you want to see your config tiddlers in the sidebar use:

<$set name="journalTitleTemplate" value={{config/myNewTiddler/Title}}>
<$set name="journalTags" value={{config/myNewTiddler/Tags}}>
<$set name="journalText" value={{config/myNewTiddler/Text}}>