From a computer or tablet:
Open your browser (i.e. Safari, Chrome, Edge, Firefox, etc...)
Point your browser to Netflix.com
Choose your profile with administrative privileges.
Mouse over the profile icon at the top right of the screen and select Account
Under the PROFILE & PARENTAL CONTROLS section click the down arrow to the right of a profile.
Scroll down and click Change to the right of Playback Settings.
Under Data usage per screen section select Low
Click Save
Repeat each of the steps above for every profile in your account. Changing the settings here will work on all of your streaming devices.

Go to settings
Scroll right to ‘preferences’.
Scroll down to ‘data monitoring’.
Scroll down to ‘set video quality.
Select ‘good’.
Keep in mind that this only affects the Amazon Video content and will not work for Netflix, Disney+, YoutubeTV, etc... You still need to go into each of your streaming apps and adjust the streaming quality there as well.