As we have said in other threads, if they are RUNNING, it doesn't necessarily mean that the fill valve needs replacing.
If it's running, it's most likely running because the seal at the flapper is failing. That's the flapper on the flush valve. Water is leaving the tank, and the fill valve is working properly to dutifully replace the missing water.
If the toilet is running and the water is overflowing the top of the overflow riser (the vertical tube) and going down the flush valve that way, then, yes, you need to replace or adjust the fill valve. Use the ones that Terry recommends above. I like the Korky better, FWIW.
The easiest test is to turn off the water to the fill valve at the wall. Mark the level of water in the tank. Leave it overnight. If the water level has dropped, you most likely just need a new flapper. Other things could be wrong with the flush valve, but step one is to change the flapper. Korky makes a number of 2" flappers that will work. Any universal one should be fine, as long as your flush valve has the little wings to attach it to. If not, you use the Korky Plus Classic Flapper (model 2000), and loop the round part around the overflow riser and push it down so it covers the flush valve hole. Easy. That flapper works fine on most toilets with wings on the flush valve; you just cut off the little loop. But as I say, there are other Korky flappers that will also work well if the flush valve has the little wings/hooks.
https://www.korky.com/
If it's gunky in your tank, it can't hurt to take a little Brillo and lightly scrub the circumfrance of the flush valve hole, where it will touch the flapper to make a seal. If there's a lot of gunk on there, sometimes it can make the flapper stand off the hole just enough to cause a slow leak.
Let us know how it's going as you move along with the project.
