Check plagiarism before submitting to journal Last year, I submitted a paper to the WISA2019 journal. Unfortunately it was rejected. So if I submit that paper to other journals, will Turnitin’s result show a high percentage of plagiarized material? I mean, my paper is already in Turnitin’s database (the WISA2019 editor checked papers by Turnitin).
As a student, if I check my new second paper by Turnitin in my professor’s class (he will give me the class id and enrollment key), will it increase the plagiarism result when I submit my new paper to a journal? The purpose is to know the plagiarism report before submitting to a scientific journal.
Are professors able to see every assignment submission that is submitted by the student? For example If I submit an essay the first time, then after resubmitting an edited essay, will the instructor be able to see the first essay which is erased by the "resubmitting process".
I'll answer question #1: No. Let us not worry about Turnitin specifically, but plagiarism is if you take someone else's text and present it as your own. That is not the case here: You wrote the manuscript, and you remain to be the person who came up with both the ideas and the actual text. It is not plagiarized, and Turnitin will show it as not plagiarized.

There is also no other issue: Since the paper was not accepted by the first journal, you continue to be the owner of the copyright in the paper, and are free to submit it again wherever you want.