how can i set values of some rows and add my custom values in action in appsheet

[heerproperties]

I want to set values of some rows and add my custom values  in that particular through creating such action .  I would like to go for multiple selection of rows and then Giving action but the values has to be customizable. Right Now  we have to assign fix values for that column and action adds only that value, but is it possible we can add any value through action button each time. 

[Marc_Dillon]

Huh? Please explain in a different way.