Hello there,

According to my knowledge ,you can select the maths standard  only one time . After selection you cannot change your standard type, The CBSE had for the first time introduced two-level Maths (Standard and Basic) in Class 10 . Basic Maths is for those who do not want to pursue the subject further and the Standard Maths is for those who want to study Mathematics as a subject in Classes 11 and 12.

So I think you had not did any mistake by choosing Standard Maths ,This will going to help you in future while Getting Admission .

There are lots of career Opportunities available if you have maths even you also have to do work hard for getting  good and High paid Jobs.

Hope this Information will help

Good Luck!