2000 Gem Beeps when charging

Just bought a 2000 Gem Car, Just replaced all batteries with AGM Deka batteries. Car drives and everything works. When you try and charge it constantly beeps.
Also not sure how to change the battery type, i see the dial but dont have a diagram for what position is what?

any help is appreciated

What code is given on the gauge? I know that ā€œFā€ is for flooded batteries and ā€œCā€ is for gel style. I am not sure what the setting for AGM would be. They are a type of flooded cell but it is absorbed into the glass mats.