Can I switch the company signatory of the deal once live?

Yes, you are able to switch the company signatory of a deal once live, however, it is not recommended if you have signed investors.  The e-signature audit trail for investors who have already signed is locked to the original company signatory, and switching the company signatory disrupts this chain, so the investors who have already signed may need to resign in order to be accepted by the new company signatory.