Has anyone had their husband pee in the sink? We keep finding a yellow liquid on the counter of the sink.

Also, is the bathroom light on during the night so that your husband can see where the toilet is?  You might need to keep the bathroom light on all night or put a bright motion sensor nightlight in the bathroom so that your husband can see the toilet.

I like the backwards walker idea.  It does work quite well to help balance a person while they are standing in front of the toilet or when they are getting up from sitting on the toilet.

The sink is also more "urinal looking" and that might be where the brain is...
Do you have a standard height toilet or a tall one with an elongated bowl? The tall elongated ones are much easier for aiming.
If it is a balance problem line DeeAnna mentioned you could try placing a walker backwards over the the toilet, pushed back so that the hand can hold the grip while standing. Also makes it easier to get up when sitting.
Another option is to try to get him to sit down when using the toilet. Easier for the balance as well as preventing dribbles.

You say in your profile that you are caring for your father “from a distance” and there’s a possibility that you will soon be caring for MIL? And your husband is having cognitive issues as well and peeing in the sink? Are you responsible for caring for all these people without help? And you have a teenager as well? Wow.

Has your husband been tested and evaluated for dementia? At the least, he may need to start wearing adult incontinence briefs. And, he probably needs supervision when he heads for the bathroom. He is obviously becoming confused and needs someone to point him in the right direction in the bathroom. He should also be supervised in other areas of your home as well to keep him safe. And, unsolicited advice, but if hubby tests out to have dementia, I would very, very carefully think over taking on the care of your mother-in-law in addition to your father and your husband.

At a couple of nursing homes that I worked at (several years ago), some of the male residents would use the bathroom sink instead of the toilet.  A couple of the men were tall and the sink was the "proper height" for them while the toilet was too low to stand in front of.  Also, they used the counter to help balance them as they peed.  They kept losing their balance if they stood in front of the toilet and they did not want to sit down to pee.

Maybe your husband is having problems with his balance and is using the counter to support his body while peeing.  😃