I want the database to "blank out" all fields in all forms for the following week
This sounds like you've based your form(s) on a table, which is something I rarely do. Basing them on a query allows you to restrict displayed records according to your needs, otherwise you load an entire table each time the form opens, unless you apply a filter on opening. If you're going to do that, then why not just use a query? I don't use navigation forms, but whatever form you're opening from there, they can make things more complicated when you attempt to pass values to an opening form. Usually, the reference to the nav form that contains the filter value isn't correct, which is one reason I don't use them (the other being that you can only have one open at a time), but you didn't post anything that really explains the process you're using. If that isn't the case here, then I don't understand what the issue really is.
If you want all subsequent forms to be be able to know a chosen date, then you need a way to a) pass this value from one place to another or b) write it to a global variable or a table and reference it from there when those forms open.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.