Thank you so much Mike, I found what you mentioned, (Preferences, then Transactions) and selected the last selection "use today's date as the default"...and it did the trick...new invoices are automatically showing today's date again. I have no idea what made it change (I've never had the problem till this weekend...) but maybe an update defaulted the setting.
Again, my sincere appreciation for your help! Wishing you a great holiday season,
Nanette