I'm going to take a stab in the dark here.

What date is showing as the default all the time?

Are you changing your session date to "today" each time you open your file?

If so, each time you open the Sales module it will put in the session date and will keep it for each invoice until you change it.

My session date is showing up as 01 October 2020. No I don't keep on changing the date each time I open the sale module. 

Thanks

I didn't say

Arsalan Qureshi said:

changing the date each time I open the sale module. 

I said

Richard S. Ridings said:

Are you changing your session date to "today" each time you open your file?

If my assumptions are correct, you need to select Setup, User Preferences, View, Show Change Session Date at Startup.

This will allow you to change the Session Date to "Today" (I just use the down arrow and hit Enter - but I never do that to transition to a new Fiscal Year).  Each module will open with the Session Date as the default transaction date.

Once you open the program, you can change the Session date from the Maintenance menu.  You can test all this right by closing all Windows in the program by using the button on the toolbar.

Then change the Session Date to Oct 4.  Then open the Sales module.  What is the date.  Close the Sales module.

Now change the Session Date to Oct 10 and hope the Sales module.  Is the date now Oct 10?

Is this the behaviour you are looking for?