Set Everyone's showsignatures to off:
UPDATE user SET options=options-1 WHERE options&1

Set Everyone's showsignatures to on
UPDATE user SET options=options+1 WHERE NOT(options&1)

Set Everyone's showavatars to off:
UPDATE user SET options=options-2 WHERE options&2

Set Everyone's showavatars to on:
UPDATE user SET options=options+2 WHERE NOT(options&2)

Set Everyone's showimages to off:
UPDATE user SET options=options-4 WHERE options&4

Set Everyone's showimages to on:
UPDATE user SET options=options+4 WHERE NOT(options&4)

Set Everyone's showvbcode to off:
UPDATE user SET options=options-8 WHERE options&8

Set Everyone's showvbcode to on:
UPDATE user SET options=options+8 WHERE NOT(options&8)