Buggy Signature

I've been trying to change my signature and it includes the use of the '  symbol on words like can't and i'm.

After i save the signature, when i view it, the symbol is repeated so the words appear like can''t and i''m.

I tried writing them without the symbol thinking that it might put them in automatically or something but they don't.

I can either not use the symbol or have it repeated, it is incorrect and looks it