How to make filled out values permanent

[echoi]

Hello all!
First time posting in this wonderful forum!
I have a workbook where I enter our few departments weekly sales by Customer name, Item number, amount and quantity.
I have tried to make things little bit more smooth and faster so I create a new workbook with two sheets.
Please find workbook link here (link in Dropbox, if is not active please let me know).
In my first sheet I have an information entry fields where I manually I'll key in customers name, item number date (month and day), amount and quantity. In the second sheet I have monthly calendar (just as a sample I put only first month), where by the following formula I call out filled info from the first sheet. Formula I use is the following:
=IF(AND($B$5=List!$B$4, $B$4=List!$D$4, C$3=List!$E$4),List!$F$4,"")

My problem is that I can't figure out a way to make automatic entries in Monthly sheet permanent and they get cleaned up every time when I change customer name or the date.
If anybody can guide me to the correct direction I'll be grateful. Also I don't mind to add VBA to my workbook (completely amateur in this field).

Regards'
Ester

 

[Leith Ross]

Hello Ester,

Are you creating new workbooks for each month?

Why is the Item Number not tracked daily for each Customer?

 

[echoi]

Hello Ross,

No, I don't create new workbooks. When a month sales entries end, I'll add new month rows and continue from there.
Actually our item numbers are unique and created based on customers order by combining actual SKUs (6-29 items). Each item number will be displayed under customer's name in Monthly sheet.