How do you change a kitchen sink trap?

Remove it, clean it and replace it.

Have you tried baking soda and vinegar?

Here is an article that might help - https://www.homedepot.com/c/replacing_drain_traps_HT_PG_PL

You probably have a clog further down the pipes. You can rent, purchase a 1/4" X 15' snake, remove the P trap and rod it through or have a plumber do it. Replacing the drain trap won't fix a clog. Also you can remove and clean the trap, but that is more likely not the problem.

https://www.homedepot.com/p/BrassCraft-1-4-in-x-15-ft-Drum-Auger-BC84150/202755043

Yes, several times, Chas. It didn't touch it. I'll check out the website you sent from Home Depot. Thank you so much!!

Then you need to remove the trap under the sink and clean it then I'd run a snake thru the pipe and see if there is a blockage.

Awe, you are so sweet and WAY TO GO!!!! I have had to snake out ours too (my daughter fills our drain with hair - lol) I'm so proud of you!!! :) Sending you big hugs my friend

I had problem with sink and the in bathroom. 3 bottles of drank over 6 months..did not work. Went to true value asking about drain plug in tub.. Complicated type. The man that worked there at ace hardware sold me flush away chemical drain cleaner. 20 minute and clean as a whistle...