DNS want more speed, security, privacy?

 For every site you visit on the Internet, your device must supply an Internet address. This is done with Domain Name System. DNS. Most WEB pages contain many individual pages to fill the page you requested. Each of those pages require an Internet address. Each address requiring a DNS service to translate a name to that Internet address. Time is cumulative. Microseconds add up to be seconds.
Using a faster DNS server should make your device load pages faster.
 The DNS server logs every name to Internet address lookup. Thus even with browsers in private mode, the DNS server can track your traffic on the Internet.
 If the DNS server is provided by a company that sells those logs, your privacy is affected.

 Using a DNS server that is faster and does not share the name lookup logs might be a better choice.
For more security a DNS service provider can block access to known bad sites. Blocking bad sites is important for both forward and reverse lookups AND them getting to you as well as you getting to them for malware getting home.

 Suddenlink provides this DNS service by default. Some users changed to Google's DNS server for increased speed and reliability.

 Recent DNS offerings from Cloudflare and Quad 9 offer faster and more secure DNS. Bad sites will be blocked before any attempts to load traffic from those sites.
Your devices use the closest DNS server. Your device will use a home router or wireless access point to do the DNS name lookup if no DNS server is setup. If no DNS service is defined in the router, the Suddenlink DNS server is used.

 DNS servers must be configured with the Internet address, otherwise there would be no method to lookup the name of a DNS server.
Quad 9 has an IPv4 address of 9.9.9.9 and a secondary address of 149.112.112.10
Cloudflare has an IPv4 address of 1.1.1.1 and a secondary address of 1.0.0.1
If your device supports IPv6:
Quad 9 has a IPv6 address of 2620:fe::fe and a secondary address of 2620:fe::9
Cloudflare IPv6  2606:4700:4700::1111  secondary 2606:4700:4700::1001

For your home router or wireless access point consult the manual provided with the device or the vendor's support site for how to view and change the DNS server. YouTube or the Internet may provide more detailed setup settings for your home router and/or wireless access points.
An example for a Linksys wireless access point

 Windows
For most Microsoft Windows systems Click the network Icon on the right hand of the task bar.

Yours may be elsewhere on the screen.

IMPORTANT: You should set DNS and other settings for any and all network adapters!

For each adapter choose Change adapter options:

The list of currently known network adapters. Detail view

Choosing Ethernet:

Now choose Properties

Note: At this point you should get a User Access Control (UAC) window popup since you should NOT be running as Administrator. Please see the Administrator post for details and clarification.

First do IPv4

In the above case the Cloudflare primary DNS server is tried first, then the Quad9 primary, then the secondary Google DNS server. You should choose the DNS server hierarchy to best suit your individual requirements.

Doing a similar setup for IPv6

Be sure to use Apply for the changes settings to take effect. Check the settings on occasion AND after major releases.

If you get a DNS name lookup block or a site will not load due to a DNS name lookup block, use care before circumventing that DNS name lookup block.

MacOS
 Again better to setup DNS for both IPv4 and IPv6
From Start or Apple icon, System Preferences -> Network -> DNS

Linux & UNIX
  edit  /etc/resolv.conf

Smart Phones

 Both Google Play Store for Android and the Apple Store for iPhone have a 1.1.1.1 Cloudflare app.

The 1.1.1.1 app has advantages: It will use a Virtual Private Network (VPN), can be quickly switched on and off, and has been shown to be the fastest name lookup at the time of this post.


Android
 Depending on your provider you may or may not have control of your android for cellular DNS.

For Wi-Fi
Settings -> Wi-Fi
Hold the network you wish to modify for DNS

YOUR screens may be different. Check your Android and manufacturer's site for your model.

iPhone

Settings -> Wi-Fi
Click on the Information circle for the network name you wish to change DNS server information.

Note, Save, then delete old DNS server IP addresses.
Click Add Server

Add entries for your choices for faster, more private, and safer DNS servers

You can consider adding the previous DNS server listed in settings at the bottom of the list of DNS servers.


Efforts have been made to check the accuracy of the information provided.
After and configuration change, test the functions for the desired behaviour. Check the SAVE buttons. 
I suggest checking the settings after major updates, upgrades, or patching.