After sftp connection with phpstorm, some questions related to file upload

Hello.
Currently, I've heard about ftp problems while using phpstorm for free version.
Rather than a problem, I will leave some questions after listening to stories about PHPSTORM about whether it is different from what I know.

1. In situations where people A and B connect to sftp via phpstorm and are modifying files other than the same file, the person A finished the work and uploaded it.
After this, if the person B has uploaded to save and ftp lastly, has the file worked by A go back to the original state?

2. When I click on the SFTP upload button, can I know if only the file that I worked on has been uploaded or whether the connected source is uploaded entirely? As far as I know, I upload only the files I worked on, and when other users complete the upload with the line drawings first, I know that the window of matching is checked by checking the changed part.

3. When working with multiple people on SFTP with PHPSTORM
Have you received any problems with the source returning to its previous state?

I listened to the above contents as it is because I heard the function completely different from the part I know.
The situation was confused because Juhyon-bun who is spitting nonsense nonsense as a user who tried using phpstorm thinking that the above-mentioned content is a meaningless talk with common sense. So I want to know exactly, please contact us like this.

I appreciate it if you can make a possible fast response.