Still not a lot to go on - answers to 2, second half of 3, and 4 are missing.
One factor of lower video image quality with DVD is the device resolution that it is played ie if it is a Full HD 1920 x 1080 or 4K TV, or similar high resolution equipment, then the upscaling of the DVD may be the cause of some of the issue.
DVD resolution is 720 x 480 (NTSC) or 720 x 576 (PAL) and you are dependant on the quality of the playback devices upscaler, at best the visual quality will be acceptable, at worst terrible.
Did you turn on the Apply anti-Interlace filter (reduces flickering) option in the DVD burn Encoder settings option as shown below.
. . . . You'll ,have to bear with me. I'm not very good with technical information. . . .
No problem, it is good to know as we can get carried away sometimes with abbreviations and technical stuff.
. . . . I play the dvd on my LG 4k player and watch it on my Samsung 4K TV . . . .
That could be part of the problem that is a big upscale for the DVD video.
What does the video look like when played on your computer? If you don't have DVD player program on your computer download and install VLC Media Player which is a free program that can play DVDs properly.