FreeFileSync Forum

I am sure this ia really simple. But after 65 years in IT (DP?) my brain is full up!
I cannot find an answer anywhere and I don't 'know' FFS well enough yet to know where to look?

I have two VERY large folders (>100Mb) with several 1000 files in each.
I will call them F1 and F2?

I can update F1 ...