Hi all,
I wonder which tense is more prefer for the following sentences, present perfect or past tense(underline ones) ?

In my accounting course work, I have emphasized in financial and managerial accounting skills. In addition to my academic foundation, I gained working experiences in accounting from my two summer internships in Hong Kong. I served as an assistant to the Senior Accounting Manager as an Accounting Staff at PoTak Limited Co., a logistic company. I assisted in managing payroll for over 60 employees monthly. I also managed the accounting of over a hundred of shipping invoices daily. Through my hands-on experience with my internships, I have become well-organized with high attention to details and accuracy. Along with the accounting skills, I have built up a solid foundation in general administrative skills as an Office Assistant at Foothill College. I gained experience in filing and data entry for students' files.

Thanks a lot! : )

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Hello, lwg-- and welcome to EF. I suggest:

In my accounting course work, I emphasized financial and managerial accounting skills. In addition to my academic foundation, I gained working experience in accounting from my two summer internships in Hong Kong. I served as an accounting staff assistant to the Senior Accounting Manager at PoTak Limited Co., a logistics company. I assisted in managing the monthly payroll for more than 60 employees. I also managed the accounting of over a hundred shipping invoices daily. Through the hands-on experience of my internships, I have become well organized, with a strong attention to details and accuracy. Along with my accounting skills, I built up a solid foundation of general administrative skills as an Office Assistant at Foothill College. I gained experience in filing and data entry for student files.
Thanks for your help! It looks much better !