Why do you want to change your thesis? First of all, English is not our mother tongue after all, and we can't avoid some problems in grammar and vocabulary, so substitution method is a good way to check mistakes, and some foreign tutors agree with and even recommend it to students. They call substitution more like proofreading. Proofreading may not be a substitute for professionalism, or it may be to show your paper to others to see if there are any logical problems, or if the sentences you write are inexplicable or ambiguous. So in fact, proofreading is possible regardless of the level of English writing. I have also read papers to roommates of foreign students, which is normal.
Of course, when you choose to write on behalf of others, I suggest that you let the person who writes on behalf of others take the notes of Word with them, instead of letting him change them directly in your article, because others will have their own habits when writing articles, which are always different from yours. After reading the notes, you can decide whether to change it or not. There are also some "dirty" substitutes, which will make you suspected of plagiarism, so you should read the contents of the substitutes carefully, and it is best to buy a Turnitin check on Taobao after finalizing it to see if there are any sentences with high repetition rate. This kind of plagiarism is very serious abroad, so the paper can be revised on behalf of others, but it must not be written on behalf of others. A friend of mine made a mistake and asked for a small homework. Black-hearted writers copy paper from the East and paste it from the West. After the friend submitted it, he was questioned for plagiarism and was taken to the little black room for questioning. Then I found the ghostwriter and blacked out my friend after collecting the money. Therefore, the grades and degrees are all your own, and the thesis can be replaced. Don't try easily. You believe, you lose.