In Charlie Recruit there are two types of email signature: your personal signature, and your company signature.
Setting Your Personal Email Signature
Head to Settings --> Personal --> My Account and scroll down to the Email Signature box to add and update a personal email signature.
Setting the Company Email Signature
If you are your company's Account Owner or Admin, you will also be able to set a company signature which will be used on automated emails.
Head to Settings --> Company --> Profile to see and edit the email signature for the company.
All done!