Retaining the value post it gets calculated by a formula

I am stuck on a problem from last few days.

Table Structure
Module ( Y axis )
Date ( X axis)

Everyday, this table gets populated automatically ( based on formula) after i enter certain values in a table present in another worksheet
12-Jul 13-Jul 14-Jul 15-Jul
278
11
56
66
129

My Formula is SUMIFS(Table3[Executed],Table3[Module],"Screen") - this is for row 1 - it will give me 278.
and same formula is copied in B2 ( considering 278 as A2)

Now, nextday, if update table3 with 13-Jul 's data, i'll get correct count for 13-Jul, but data for 12-Jul will also get updated ( which i dont want)

I want a mechanism by which i can ensure that the value calculated by formula on 12-Jul should get retained and should not change, once i update data next day.
is there any way in which i can retain the value once it is calculated by formula ( i do not want formula to caculate the value again, once it is populated by a numerical value)

this can be done via an automated macro..

I'll be extremely thankful, if you can let me know the steps for this

please send me a sample (non sensitive, of course) and I 'll walk you through it.