It depends on the load
I have a SQ FL and softened water.
A heaping teaspoon of Tide HE powder is the right amount and makes generous suds, but not too many suds to interfere with wash action, with a load of towels.
With a load of tidy whities, it takes 2 level teaspoons in the prewash and 2 more level teaspoons in the main wash. I do a prewash so that the main wash will be hot and stay hot. There are two reasons so much more is needed for the tidy whities. Anti-perspirant in the undershirts kills suds and is difficult to remove and the undershirts, being in direct contact with skin all day, pick up more body oil and perspiration than other garments.
Generally, if you wear clothes only once and don’t perspire in them, then a teaspoon to heaping teaspoon will be correct. If you wear clothes more than once or sweat a lot in them, you will need more.
It all depends!
If you are washing only one load of clothes a week, chances are high you are way overloading. Drop or toss garments in the tub. Do not compress at all. Leave say 3 or 4 inches at the top. When everything is wet the level of clothes should be an inch or 2 below the level of halfway up the window. Any more than halfway, it’s overloaded. When tumbling there should be an ellipse so that all the clothes are dropping and slapping on the tub, with none caught in the center just rotating.
Ammonia (clear, non sudsy) is my vote for getting dirty clothes or sheets clean. It gets that sweat odor out of dress shirts every time. In your case soak them in ammonia for say 30 minutes. A scant 1/4 cup in the SQ FL is what I use.
Lastly, rinsing is all important too. Push both the second and third rinse buttons so you get a total of 5 rinses. You need that many.
Oh — and purging cold water from the hot water line is essential too. Really, you should wash everything in hot for awhile to get built up body oil out. It,s probably going to take several washes.