Is it possible to only enable signatures for particular categories?
I’m afraid that’s not currently possible, but I’ve moved your suggestion into the ux category to see if other people have also felt a need for this. 
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It would seem like you could css hide them by category?
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That’s true. I should’ve said, ‘in the UI’.
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Okay, thanks. I am trying to stumble my way through learning CSS so we’ll see if I can sort out making that change!
There are some topics and/or theme components that do stuff in certain categories, so you might search for those.
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