I am done trying to help you.
You have the solution to keep your photos in one place, which is ICloud Photo Library.
I am assuming, because you have not provided details to the contrary, the photos being synced via iTunes ARE ALSO in your local photos library.
If so, ALL of your photos in your local Photos Library will sync to iCloud and after that, will sync to your device. One library in 2 "safe" places.
As part of that process, you MUST remove the iTunes synced photos from your device. After that the iCloud Photo Library syncing process will put them back on your phone. You have no choice.
Please read the documentation for iCloud Photo Library. Nobody here can read your mind to figure out what you want, what you know and what you don't know.
https://support.apple.com/en-ca/HT204264