Nothing has changed in this respect between versions. Possibly your
default shortcuts have been removed or overwritten by something, such
as a badly written add-in.
I assume -- though you didn't bother to say -- that you now have Word
2007. If so, go to Office button > Word Options > Customize and click
the Keyboard Shortcuts Customize button in the bottom left of the
dialog. In the categories list, click Home Tab. In the Commands list,
click Subscript. By default you should see Ctrl+= in the Current Keys
box. If it's not there, put the cursor in the "Press new shortcut key"
box and press Ctrl+=, then click the Assign button in the bottom left
corner of the dialog.
If it's Word 2003 or earlier, click Tools > Customize and click the
Keyboard button. From there the instructions are the same as above.
--
Regards,
Jay Freedman
Microsoft Word MVP
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