I have scored 41% in class 12th with commerce stream. Should I continue in 12th with commerce stream or go for arts stream?

Dear, Firstly, you need to check with your school and rules too for change of your stream in class 12th and consult with school counsellor and speak to your school teachers too regarding this, take the decision accordingly. Don't take decision like this. All the best.

You can carry on with your commerce stream. I know you are weak in commerce but it will help you in further studies whether you pursue CA, CS, CFA, MBA or any other course.