我无法弄清楚如何正确地输出所有信息到文本文件

I'm working on this project and I can't figure out how to get all of my info to out put to the text file it seems to only output the last bit of info that was input. Before putting in the new header before the averages output I could only manage to get it to place the average in the text file. Help me please!I'm working on this project and I can't figure