Auto-update values (guessing, IF formula...)

Hi, can I ask for a suggestion, how to help eliminate manual work updating file every month?

All details are explained in a file attached, but basically, I get days and weeks moving around with every new month selected, and challenge is: to get end of week results I need to be updating end of week formulas for every new month. Such a waste of time...

Here is a file:

https://www.excelforum.com/attachmen...1&d=1506882379

There are existing formulas there already, only they dont do a proper work...

Thanking in advance!!