The creation and customization of database applications using Microsoft Access
I took a look at the sample accdb. If that is real data, I urge you to remove it from that public Dropbox location where anyone can get to it.
That said, everything is working as it is currently set up, so what we need to know is WHY you want a different result.
The query called TempBO filters by date. It returns 7 records for the hard-coded date in it because that's how many records have that date.
In the subform, your query, called BackOrderSubForm, filters on two fields: Job and SO# (which is a dangerous name for a field in a table, btw). So any record in the table which has those three fields in common will be displayed in the subform. There are 4 such records among the 7 filtered by date and by JOB 880035 and by SO# 501800. There are three such records among the 7 filtered by date and by JOB 880034 and by SO# 201800. When you look at any record in the subform among the 7, that's what you see.
Interestingly enough, the size of the subform allows only 3 records to be visible. It has scrollbars disabled, so that hides the fourth record in it, thus potentially misleading the user about the results. They'd never see the fourth or later records in the subform!
Explain what you DO want to see. There are 7 records, as filtered by the selected date -- that would change, of course, for other selected dates. The subform filters according to the parameter in the query which is its recordsource, by JOB and SO#. Because the there are two different JOBs in the 7 selected for the date, 4 will appear in the subform with one JOB and 3 will appear in the subform with the other. The "hidden" row in the subform -- due to lack of scrollbars and insufficient display height-- probably confuses things.
So, in order to suggest changes, other than adding the vertical scrollbar, we need to know, from a business perspective, why this is not accurate and appropriate.