In addition to xabbu’s post, changes to /etc/resolv.conf are generally temporary: "If resolvconf is available DNS information will be sent to it, if not, then dhcpcd itself will write to /etc/resolv.conf. openresolv is a resolvconf implementation and “is most known for allowing multiple applications to modify /etc/resolv.conf”
To set DNS, add this to /etc/dhcpcd.conf:
static domain_name_servers=176.9.37.132 195.10.195.195
For more info, read this.