Please Correct The Mistakes in This Entry

I am a junior in highschool, I am studying accounting. a student in accounting departement
Lately my grades have dropped become quite low,I suppose it is because I abandoned my lessons for learning languages. My grades weren't aren't really high from the beginning but it dropped significantly. 
Learning accounting is really tiring for me, so I decided to not really focused on learning it anymore and focus on language learning. 
I wonder if it's a wise desicion to make. choose

please correct the mistakes in this entry

I am a junior in high school. I am a student in the accounting department. 
Lately my grades have become quite low. I suppose it is because I abandoned my lessons for learning languages. My grades aren't weren't really high from the beginning but it they dropped significantly. 
Learning accounting is really tiring for me, so I decided to not really focused in on learning it anymore and focus on language learning instead.
I wonder if it's a wise desicion to choose make.

It's hard to focus on classes that you don't enjoy. I hope that language learning makes you happier! :)