ātitleā alone is ambiguous. Iāll start by assuming you mean in map view. I donāt think centring in all views is possible, and for some would make no sense so to do.
Titles of notes in map view are controlled via $NameAlignment (N.B. in the system attribute āMapā Group).
$TextFont is used to set the font face of a noteās body text ($Text). $TextFont in the Inspector looks like this:
Firstly, note the there is not āTextFontā Group, rather it is TextFormat. Within that Groupā is attribute $TextFont. It is the font(face) for the $Text of notes.
As the attributeās Default box indicates, this setting is not made by text input but via the documentās preferences, also called Document Settings. The latter is opened via the Edit menu or shortcut ā+8. In the settings, dialog, select the Text tab, and use the Text Font control to choose the face ($TextFont) and size ($TextFontSize) as the default for the document:
Clicking the font buttonāthat shows the current font face/sizeāopens the macOSā Fonts palette:
Note, for setting document preferences only the face and size are usedā”.
Re title vs. text. In the Text pane of a document you see this (with a Map as the view paneās selected view type):
).
Or same note, but now in Gaudi view:
See how the text pane (at right) has the same presentation even if the view pane (at left) changes its view type.
Note the title ($Name) is used as the label of the view icon for the note and is shown above the noteās text ($Text). In map view only, depending on the map iconās size you may also see some of $Text rendered on the icon below the $Name (note title).
Note that Tinderbox uses rich text in the text pane text area (The $Text content) but the app is a not Word Processor (like MS Word), so thinking in those terms when trying to style text is likely to be unhelpful, e.g. Wordsās saved text styles. A closer app to consider in this regard is Apple TextEdit. That has limited style support hidden away in its Format āø Font āø Styles⦠menu. I believe Tinderbox supports some of the latter via menu Format āø Text āø Ruler to show the $Text area ruler, then open the Styles and then Other⦠from the pop-up list. As this might indicate, Tinderbox users donāt much use word-processor type styles: or if they do, they donāt discuss the issue.
If none of that answer the question, please describe (or show via a screen grab) what you have in mind for the meaning of ātitleā. As youāll see from the various answers Iāve had to give above, it isnāt unambiguous! 
ā . The system attribute Groupsā role is to split the 400+ system attributes into groups of (roughly) associated roles. As the app has grown, so have some groups. When using the Inspector search, it is the attributeās name that is matched, i.e. what is selected in the Attribute pop-up list (as in the image above of the Inspector
ā”. The colour of a selection of $Text can be set via the Fonts palette. The default $text colour is set in $TextColor via the Document Settingās Tab paneās text colour controls. Bold/italic are set via Tinderbox controls and use the default fontās bold-or italic face if on the host OS system. IOW you canāt set italic $Text if $TeXtFont has no italic face: same for bolding.