On/Off stat increase

How can I make a macro which can increase one or two stat depending on situation?  I want to be used as an on/off thing which can be activated by player/gm if needed. To give some flavour this what I want to emulate: Pit Fighter. The warrior has learned how to fight in enclosed spaces from his time in the dangerous fighting pits of the Empire. He is an expert at fighting in confined areas and adds +1 to his WS and +1 to his Attacks if he is fighting inside buildings or ruins.

Normal macros can only read from a sheet, and cannot change values. Scripts can change values, but the GM of your game needs to have a pro subsction and then install a script that enables it. The specific example you're listing cant be done without also rewriting all the attack macros used in your game (or at least the one macro you want tp use in that way) - and also would likely require a lot of separate popup queries, which gets irritating fast so you are better off just remembering the modifiers and manually applying them as needed.

If you do want to try automating, ChatSetAttr is the goto tool for automating changing values on character sheets. Specific macro code would depend on the sheet you are using.