linuxmint cinnamon 19.4 ubuntu/how in the heck do you know what the superuser password (root) is if it keeps locking you out of everything?

i am new to linux coming from a long history of windows xp, 7, 8 and 10. My system is a acer-aspire 1420 500 hard drve, and 2gb memory. It does not seem that linux is working right wont update security info, download programs, or let me in to do disk formatting. Keeps asking for root password for slowroll???? iv tried to change it but no work for me HELP
lol