Macros to subtract from attributes

Hi all, Pretty new to Roll20 and Macros. I will be running Earthdawn 3rd Edition, and I was wondering if someone smarter then me could advise me on Macros. To help you understand what I'm trying to achieve, I've included some screenshots below. In this system, some of the Talents use a resource called Karma. I have put in the 'attributes' character's karma and made it show as a bar over a token to make in easier to see how it depletes. I have also done simple macros for all the talents so that you can roll straight from the macros available to each token/player. Is there a way to set the macros for some of the talents to automatically subtract karma from the character? Hope this all makes sense, but if not please let me know and I'll endeavor to explain better.

Unfortunately, macros can only read attributes from a character sheet. They cannot write to them. That would require an API script (Pro subscriber perk), such as ChatSetAttr.

keithcurtis said: Unfortunately, macros can only read attributes from a character sheet. They cannot write to them. That would require an API script (Pro subscriber perk), such as ChatSetAttr. Thanks for the tree reply.  I do have a pro subscription, so if there's a way to do that I'd much appreciated the guidance, I've not had anything to do with API yet, so version for dummies, please.

Just checking, because I see a "Plus" next to your name. Do you have a separate subscription?

Oh no, sorry, I got the naming wrong. I have the lower tier paid subscription.