I am using Ubuntu 18.04 and Window 10 on the same machine (dual boot) and recently I have upgraded the RAM from 4GB to 8GB. After that window-10 still used 4GB instead of 8GB. I had performed the "factory reset and reinstall window-10" to make Window 10 to use 8GB RAM. But now I am confused about is Ubuntu 18.04 using 8GB or 4GB of Ram? And have I to do reinstall ubuntu just like the window 10 so that it can use 8GB in ubuntu or some other actions.
I have attached some screenshots that clears the current state of RAM.