Urine on clothing. Any advice?

This is going to sound stupid, but bear with me. I don't know how well it would do with human urine, but my one cat had a habit of urinating on our bath mats or towels left on the bathroom floor. After much trial and error, I found that running them through a rinse cycle of COLD water and then washing them in COLD water (with the baking soda and detergent) eliminated the smell. Previously, when I used warm or hot water, it seemed to actually enhance the odor. It could be worth a try.

Clorox makes a Urine Remover that works well.
OdorBan works very well also. The OdorBan mixed in a higher concentration is also a sanitizer not just an odor remover. (and it is enzyme based so it removes odor does not cover it up)
Is dad wearing incontinent underwear? Either Pull up or tab type?
If not you need to remove all his cloth underwear and have him use disposable underwear.
If he is currently wearing incontinent underwear and it is leaking through there are pads that you can use they will absorb a bit more. Do not double up on the incontinent underwear as the water / moisture resistant lining will prevent the other one from absorbing all it can.

It’s not about the type of soap or washing machine setting.
Does he wear pull-ups or diapers? He’s incontinent, so he can’t wear regular underwear. & needs to be reminded &/or taken to bathroom. He’s needing help in bathroom too. He will have #2 in trousers soon…get him in disposable pull-ups or diapers Hugs 🤗

Get him to start wearing incontinence underwear. That's first.

Have you tried using a different detergent? My girlfriend swears by arm and hammer with oxyclean, she even cleans her carpets with it. I have never smelled urine in her house. She uses vinegar to rinse and no fabric softener of any kind.

No high heat drying either.

If it’s a front loading machine, unfortunately they don’t use a lot of water either during an actual cycle.

For any soiled items I cold rinse first, sometimes twice with odour / antibacterial removal (without other clothes in there for maximum water), followed by normal cycle (can add other clothes at that point). I find lavender softener the best counteractive scent.

Also has he had a urine test?
Urine can smell extremely potent if there’s an infection! I know Mums urine smell hideous when she’s getting a UTI and those times her clothes / surroundings smell worse until the antibiotics take over.

Incontinence underwear and disposable incontinence pads where he sits or under him when he sleeps are the best prevention. Good luck with the other cleaning suggestions. All the best to you both!

Use 20 Mule Team Borax Laundry Booster, Powder in the wash, and 1/2 cup of vinegar in the extra rinse cycle. Works great.

Go to the pet dept at the grocers. Get Nature’s Miracle or something similar. Works on rugs etc. fairly well. I also use OxyClean

White Vinegar in the wash - just dump some in with the detergent - works well.

That happens when you convert a regular home into a nursing home. It's admirable what some people do to care for their sick old-relatives. My deepest respects to those caring souls. I certainly won't let my daughters go through that.