Can someone please set me stright on which is which i have googled it but to be honest have found things saying both back and front of uterus for a posteria placenta

I have a grade 4 placenta previa and was led to believe it is at the front so it would be difficult to have a c section.
All my appt the docs have been unable to hear bubs HB as the placenta is in the way and that is all you can here is the blood pumping through that.
so i assumed they ment it was in the front
But when i googled it i found anterior is the front and posteria is the back so looking through my u/s reports i read that my placenta has moved more over the cervix 1st scan said placenta posteria 2nd scan says posteria low then the 3rd and 4th scan both say posteria low totally covering the os and they were 4 weeks apart so i am a little confused if my placenta is posteria then wouldnt that be ok for a c section as it is on the back wall of the uterus and low over the cervix not in front where the incision would be?
I have read different things and cant seem to get a conclusive answer is posteria the back wall and anterior the front wall.