Hello Raghavendra,
Here, you can enter the dates as per your period requirement date, and enter the target day's. as you have only one month period you can use this functionality.
ex. suppose you have planning for 4 weeks period and you set the target day's 5 for all these 4 period.
Now you want change the one of the week period target day's from 5 to 3, in that case period date enter period from to period to and set target day's 3 as per your requirement.
You can enter individual period from and period to date and set the target day's with in one period.
please check and confirm.
This is the only way you can achieve your requirement.
Regards
Umesh Mali