I want to know the calculation method of fold change

Hello, the designers of this forum. Recently I met a problem that confuse me a lot. Actually I have a group of metabolomics data going through the data analysis through this metaboanayst. I used the data normalization including normalization by a pooled sample from group (group PQN) and auto scaling. Then I uesd the volcano plot for screening the differential metabolites. However, I can’t figure out the fold change calculation method for the specific metabolites. As we know, the definition of fold change was meanA divided by meanB. But the result of volcano plot on the website was unexplained and unequal with the equation above. So I wish to get the real answer from this platform.

You can visit the Fold Change Analysis page.

How can i visit the Fold Change Analysis page?Can you give me a link.