No, he's asking how to set the default for a chemical so every time you go to enter it in, you don't have to scroll to select it. I have the same issue, and it just started a month or so ago. I have always used 31.45% muriatic acid. When I click on pH after entering values it used to default to 31.45% and tell me how much to add.
It now pops up showing Dry Acid, and I have to specifically select 31.45% muriatic every time. It is a little annoying, and I know the first time or two it happened, I didn't even notice it was giving me values for Dry Acid.
I think the app used to remember the last chemical used, and defaulted to that. It doesn't anymore. There should be a place to set defaults chemicals used for each specific measurement.