You misunderstand the form/system.
When you are filling out a form you are filling out ONE form, identified by a tiny number in the top, left corner next to the word "ACTIVE". Your currently active form is 73460. The form is not connected to particular dates; there is no "March" form, or "April" form. The forms are whatever you want them to represent. Some people put 3 months of work on one form.
When you click on the blue "Date" arrows, you are not changing to forms for different months. You are CHANGING THE DATA IN THE DATE COLUMN FOR THE CURRENT FORM. Those blue arrows are there just to save you typing. Again, you are not switching to a different "page", or the form for a different month. The entry you made "April 17" you were making for the current active FORM.