- Double-click any of the equations you want to change.
- Change the font & size to whatever you want. (In MathType -- Style > Define, then Size > Define.)
- Close MathType.
- The equation you just changed should still be selected. Copy it.
- In Word, one of the menus (or tabs on the ribbon, if you're using Word 2007 or 2010) will be labeled MathType. In that menu, click the Format Equations command.
- There are 4 "radio buttons" in the top section of the Format Equations dialog, and probably at least one of these is grayed-out. Click the one labeled "Equation on clipboard". Make sure "Whole document" is selected in the bottom section.
- Click OK.
Sit back and watch the fun. For a document with 50 equations or so, it should only take a few seconds, then it'll pop up a message telling you how many equations it changed.