I think what I'm trying to say it would be nice to know what I'm looking at for instance, fuel trims what should they look like on a healthy Tahoe compared to what the scanner is telling me.
unless you suspect a problem I wouldn't worry about it, like Fless said do a little research then look at "live data" on your scanner.
if you are throwing e85 in it then the alcohol content can get out of whack and maybe cause some problems in which case you can reset everything. (which you can do)
your ancel scanner as well as almost any other scanner is only going to do so much, there is very little to nothing you can change or modify outside of diagnostic testing procedures. then it goes back to normal.
there is no magic pill scanner that will let you modify anything permanently, that type of thing requires something like a autosync that is married to your vin and has been programmed to do what you want and even then some of it requires that the device remains plugged in.
gm has the software locked down so modifying it requires reverse engineering.