DonorWise allows you to create a batch in a previous period by "temporarily opening" a previous period. When you temporarily open a previous period, the next batch you create will take on the past period you specified. After you create this batch, the period will resume to normal, and if you want to create another batch in a past period, you'll have to logout of DonorWise and login again (this process is intentionally made cumbersome).
This topic is touched on in this help topic on Back Posting.
Temp opening a past period only applies to the very next new batch you create. This can be used with "Reverse and Start Over" (which essentially creates a brand new batch).
To demonstrate this, let's correct the date on some donations and move them back by four months!
First, I temp open the period on the Periods and Closing screen:
Now, it shows that April 2018 is the temp open period:
Now, I find the donations back in August of 2018 I want to change the date on, and I select "Reverse and Start Over".
Notice that it prompts me for a period, pre-selected on the temp open period:
Now, I can edit the date (anywhere within April 2018), along with any other aspect of the donations.
Now, the period is back to what it originally was. I can't temp open a period again until I logout and log back in to DonorWise.