To update your company name, description and logo across events, you can navigate to the 'Company' tab from your recruiter portal, and update details from there:

(Note that only the 'Employer Admin' role has this ability)

To change your own email address, click on the Profile icon on the top right corner of the screen, then select Profile, then Log in & Security.

From there, hit the pencil icon to the right to change your email or password.