@gischpelino
Thank you for that, it worked

Because I did not follow through the instructions procedure upon installing I'm kind of reluctant to use TWRP now it is installed (only changed 'Keep System Read Only' into allow changes) , frankly I'm not sure whether it'll do more harm than good going through all options available. Too scared of the unknown I guess.....

How to check if I still need to change that into ext4 format?