Equation chapter & section breaks are visible in red type

1. Sometimes simply clicking the Show/Hide icon on Word's Home tab is all you need to do. The icon you're looking at looks like this in Word 2016 for Windows:. Appearance in other versions of Word is similar.
2. If nothing happens when you click the icon, click it again. Sometimes it takes 2 clicks to reset the visibility.
3. If that doesn't restore the visibility of the breaks to "hidden", proceed to Method 2.

Method 3: Modify MTEquationSection style

1. A Word style controls the formatting of equation chapter and section breaks. You've seen Word's styles, even though you may not fully use them. They're identified by names like "Normal", "Heading 1", and "Title". It's a convenient way to apply formatting to a document consistently, and proper use of styles will prevent many headaches down the road. The name of the style controlling equation breaks is MTEquationSection style. Another associated style, named MTDisplayEquation, is discussed in TechNote 156.
2. Neither of these two styles will exist in the document until you insert a numbered equation, an equation number, or an equation break so if you're working with a new document and you haven't yet inserted a numbered equation, do so now.
3. If you're using a Mac, proceed to the next listitem. On Windows, to find the MTEquationSection style and modify it click the dialogue launcher at the lower corner of the Styles group of the Home tab . When you do that, you'll see the MTEquationSection style near the top of the Styles panel (screenshot on left below). If you hover the mouse over that style, you can see the complete definition for that style. Note: If the MTDisplayEquation style is present but not the MTEquationSection style, select the MathType 7 tab in Word and click Insert Number. Proceed to step 5.
4. If you're using Word 2011 on Mac, click the Manage styles icon on Word's Home tab . If you're using Word 2016 on Mac, click the Styles Pane button on Word's Home tab . When you do that, you'll see the MTEquationSection style near the top of the Styles panel (screenshot on the right below). If you hover the mouse over that style, you can see the complete definition for that style. Note: If the MTDisplayEquation style is present but not the MTEquationSection style, select the MathType 7 tab in Word and click Insert Number.

5. Click the downward-pointing triangle to the right of the MTEquationSection label, then Modify ("Modify Style..." on the Mac), and you'll have an opportunity to change the style's definition.
6. In the lower-left of the Modify Style dialogue, click Format, then Font.
7. In the Font dialogue, click the box labelled Hidden so there's a checkmark in the box. Click OK, then OK again. You may close the Styles pane now if you'd like.

We hope this has been helpful. As always, please let us know if you have questions about this or if you have additional techniques that work. We'd love to hear from you.