How do I change the default font in PowerPoint?

PowerPoint has this default font called Calibri (Body) and Georgia (Headings). How do I change this, such that I can have, for example, Helvetica Neue Light (Body).

In case you ask why I want this, it's because I'm doing quite a lot of copy-pasting at this point and it's annoying that the pasted text comes out in Calibri (Body).

I'm using PowerPoint 2011 on OS X.

You need to

Select and format a text shape to taste Ctrl+Click (or rightclick) the edge of the text box Choose "Set as Default Text Box" from the popup menu.

This will set the default for the current presentation. It won't affect what happens in other presentations, already created or new.

Under the "View" menu, choose View -> Master -> Slide Master.

Then in the master view, choose the type of slide and you want to change default fonts, Then choose the texts you need to change font formats, and choose the font type you want either from Format menu, or the toolbox. Now when you add a new slide of the specific type you just set up, the default font will be the one you just choose in the master view.

I usually choose the top one in the master view, and change fonts format there. Then basically whatever slides I insert later, will have that font type by default.

It's not possible to create a Font Theme in PowerPoint 2016 for Mac, it's only possible on the Windows version, for some reason. However, it's simple enough to create a Font Theme of your own. Copy and paste the following into a text editor (I recommend Visual Studio Code, but any plain-text capable text editor like TextEdit will do):

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<a:fontScheme xmlns:a="http://schemas.openxmlformats.org/drawingml/2006/main" name="Test">
  <a:majorFont>
    <a:latin typeface="Helvetica Neue Light"/>
    <a:ea typeface=""/>
    <a:cs typeface=""/>
  </a:majorFont>
  <a:minorFont>
    <a:latin typeface="Helvetica Neue"/>
    <a:ea typeface=""/>
    <a:cs typeface=""/>
  </a:minorFont>
</a:fontScheme>

Then save the file at the following location:

~/Library/Group Containers/UBF8T346G9.Office/User Content/Themes/Theme Fonts/Helvetica Neue.xml

You can browse to this location in Finder by holding ⌥ while clicking the "Go" menu item to go to the "Library".

Once the file is in place, restart PowerPoint, open the presentation, click View → Master → Slide Master, then click the "Fonts" dropdown and the "Helvetica Neue" Font Theme should be available for selection. Clicking it should import the Font Theme to your presentation and if you save the presentation as a template, it should be there for all users of the template.

1. Click on any blank area of the slide or outside the slide. You want to make sure that no object on the slide is selected.
2. Choose Format > Font... and make your selections for font style, color, size and type.
3. Click OK when you have made all your changes.

Please not these will only affect future copy/paste, the previous text will remain with the same fonts.