Comments

 

Why is it not possible to update comments after entering a trade?

 

Why do you need this?

Maybe there is another solution to what you are looking for.

 
zm95wh: Why is it not possible to update comments after entering a trade?

MT4 was created over 15 years ago. Only Metaquotes could tell you why that decision was made that way.
          Metaquotes language: OrderComment() is not able to be modified - Expert Advisors and Automated Trading - MQL5 programming forum 2013.08.10

Not a good idea to use comments, brokers can change comments, including complete replacement.