In the FlexPay client portal, you can search/filter for data by choosing a specific date or date range.
On the right header, just below your account name, there is an icon of a calendar showing the date.
Click on the downward pointing arrow and two calendars will open up to allow you to select the start and end date for the period of interest. First click the start date, then click on the end date. The selected date range should be highlighted in blue. Quick toggles for the last 12 weeks or last 6 months are on the left side of the calendars.
You may also select a single day by selecting the date twice.