Is it a combobox on a worksheet?
If yes, is it from the controltoolbox toolbar?
If yes again, then show the controltoolbox toolbar
and click on the design mode icon.
rightclick on the combobox and select properties.
Locate Font and select it. Click on the ellipsis (...) to the right of the font
name.
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If it's on a worksheet and from the Forms toolbar, then you can't change the
font for that.