Thanks John, I followed your instructions exactly and it keeps changing the
date to the current date, it is not holding the date I created the record.
All records have today's date.

An I think *you* are mistaken!

The DEFAULT is only applied when the row is first created (INSERT INTO)
and then only when no value was supplied. It don't stop users from
changing it (UPDATE). Try this

CREATE TABLE Test1
(key_col INTEGER NOT NULL PRIMARY KEY,
data_col INTEGER NOT NULL,
created_date DATETIME DEFAULT DATE() NOT NULL);

INSERT INTO Test1 (key_col, data_col, created_date)
VALUES (1, 1, #2020-12-31#);
-- created row with noncurrent date

UPDATE Test1
SET created_date = #1987-01-01#
WHERE key_col = 1;
-- changes also to noncurrent date

You say "That value will not change thereafter" but I just changed it!
Post back if you saw the current date, you may be running it
incorrectly.

The proper solution.

Logon to database as Admin, then

CREATE USER JohnV;

REVOKE ALL PRIVILEGES
ON TABLE Test1
FROM JohnV;

GRANT SELECT
ON TABLE Test1
TO JohnV;

CREATE PROCEDURE AddTest1
(:key_col INTEGER, :data_col INTEGER)
AS
INSERT INTO Test1 (key_col, data_col)
VALUES (:key_col, :data_col)
WITH OWNERACCESS OPTION;

GRANT UPDATE
ON OBJECT AddTest1
TO JohnV;

CREATE PROCEDURE UpdateTest1
(:key_col INTEGER, :data_col INTEGER)
AS
UPDATE Test1
SET data_col = :data_col
WHERE key_col = :key_col
WITH OWNERACCESS OPTION;

GRANT UPDATE
ON OBJECT UpdateTest1
TO JohnV;

Logon to database as JohnV, then

UPDATE Test1
SET created_date = #2002-02-02#
WHERE key_col = 1;
-- fails, cannot change created_date

INSERT INTO Test1 (key_col, data_col, created_date)
VALUES (2, 2, #2011-11-11#);
-- fails, cannot create row using created_date

EXECUTE AddTest1 2, 2;
-- success, created date is current

EXECUTE UpdateTest1 2, 999;
-- success, created date still is current

Is the form bound to the table in which InvoiceDate is a field (or to a query
based on the table)?  If so, right click the control, click Properties, click
the Data tab, clear whatever is in Control Source, click the down arrow, and
select your InvoiceDate field.  That's all.  You don't need an = sign or
anything like that.
Your problem was that you set the Control Source to the current date.  That
makes the text box an unbound control that gets its value from the computer
clock.  Setting the default value for a table field to the current date means
that a new record (one in which the field is blank) will contain today's date
in that field.  If you go back and look at the table I expect you will find
the field is populated with the date on which you created the record.  You
just need a way of getting that information onto the form.  A text box bound
to the field is the way to do that.  The date will not change unless you do
so deliberately.  You can lock or disable the control if you need to prevent
changes, or you can implement any level of security you may need, but I
didn't take your question to be one about security.