How do I add the records for our careers address?

Add each record Masthead shows, one at a time, using the Copy buttons. Most places want only the first part of the name (careers, not careers.yourcompany.com), which is how Masthead shows it. Leave any TTL setting as it is. If there's already a record with the same name and nothing uses it, delete it first.

Not sure where your domain is managed? Type it at lookup.icann.org and look at the name servers: domaincontrol.com is GoDaddy, dns-parking.com or hostinger is Hostinger, ns.cloudflare.com is Cloudflare, registrar-servers.com is Namecheap, googledomains.com or squarespacedns.com is Squarespace.

GoDaddy:

1. Sign in at godaddy.com, open My Products, and choose DNS next to your domain.
2. Click Add New Record, choose the type, paste the name and the value (for a CNAME, GoDaddy calls it Points to), and save.

Hostinger:

1. Sign in at hpanel.hostinger.com, open Domains, choose your domain, then DNS / Nameservers.
2. Choose the type, paste the name, and paste the value into Target (CNAME) or TXT value, then Add Record.

Cloudflare:

1. Sign in at dash.cloudflare.com, choose your domain, then DNS → Records → Add record.
2. Choose the type, paste the name, and paste the value into Target (CNAME) or Content (TXT).
3. For the CNAME, click the orange cloud so it turns grey and says DNS only. With the orange cloud on, the secure certificate can't be made.

Namecheap:

1. Sign in at namecheap.com, open Domain List, click Manage, then the Advanced DNS tab.
2. Under Host Records, click Add New Record, choose the type, paste the name into Host and the value into Value, and click the green tick.

Google Domains, now Squarespace Domains (including many Google Workspace domains):

1. Sign in at domains.squarespace.com with the same Google account, choose your domain, then DNS.
2. Under Custom records, click Add record, paste the name into Host, choose the type, paste the value into Data, and save.

If someone else looks after your website, send them the records Masthead shows. If Check says the TXT record can't be found, make sure only the first part of the name was typed (a box that adds your domain by itself can make careers.yourcompany.com.yourcompany.com). If the certificate is still being made after a day, check the Cloudflare cloud is grey, and if your domain has a CAA record, that it allows letsencrypt.org. If Masthead says another company already uses the address and it's yours, write to hello@1936ai.com.