Am Very concerned, looking for insightful info for this delicate situation:

Only 74,000 miles on our 2012 Galant Auto 4spd 2.4L.

Drained Trans fluid myself at about 71,000 miles from the magnetic 24mm drain plug and cleaned the magnetic tip.
I don't remember how bad the fluid was but it may have been original, it was time for it or perhaps overdue.

So I refilled with "Valvoline Max-Life Multi Vehicle Fully Synthetic ATF", which some resources say is appropriate.

Now, some 3,000 miles later, I noticed the dipstick wiped on a white paper towel looked dirty...
I figured, ok so the old fluid left in the torque converter has just made it dirty and I need one more change to get it sweet red.

So I bought some more of the same Valvoline ATF from my local Walmart.

Drained the fluid from the Transmission drain plug as before....AND THE FLUID WAS NOT RED BUT A DIRTY GRAY AND MAGNET HAD A HEAVY BUILD UP OF FINE PARTICLE.
Well I rechecked the internet still predominantly says this Valvoline fluid is SP III approved and should be just fine. Although one auto parts store said I should use Dextron 6(vi).....

So I went ahead and added the same new fluid again.
BUT I'M VERY CONCERNED EITHER THIS ATF FLUID IS NOT APPROPRIATE AND THEREFORE I NEED TO CHANGE IT ALL OUT or perhaps I don't have the correct amount of fluid in the Transmission which is causing a problem. I'm concerned it's a multi-vehicle type fluid may have short comings, trying to cover multi vehicle requirements...

The transmission shifts very normally.

1. Can anyone pipe in about the Valvoline Max-Life is ok or a No No?

1.a. If I need to change the Max-Life all out, can I get it out of the torque converter in one go as well AND which ATF fluid should I use and who can I buy it from, hopefully I don't have to go to the stealership (I mean dealership).

2. Am I using the proper technique to check the ATF fluid level: With engine RUNNING/Idling, shift through the gears, place in park, make sure the fluid is in the cold mark level, Drive vehicle around to normal operating temp and park wit engine RUNNING/Idling and make sure fluid is in the hot mark level.
The manual doesn't say with the engine running but I think that's what it meant.....same as how most traditional transmissions are most often checked.

Thank you for any help!