DNS & DKIM + SPF

Okay, so this has me confused a bit, so I thought why not take a second opinion. I feel like I forgot everything. I have a domain whose Nameservers and DNS is managed remotely on Google Cloud DNS. Somehow, the DNS zone is also visible in WHM > DNS Functions. (Why?) Also mail server in WHM is Remote Mail Exchanger[Google Suite]. So since there are two DNS zones, there are also two entries for every record - one on Google and one in WHM. For the most part it is fine since all eventually point to a single IP address. However, as far as DKIM and SPF are concerned, it is a problem - since keys for both are different. Enabling DKIM/SPF globally, didn't change the values which already exist in Google DNS. So what DNS zone is actually being used here, and which DKIM/SPF values are being read?