Well, no, what you've just written is exactly wrong. DNA changes all the time -- the process is called mutation. It's happening in a big and important way right now in the SARS-CoV-2 virus (except it's RNA, not DNA for the virus). There is no evidence whatever for limits on how much DNA can change.
Addendum re. DNA:
God designed DNA to only create variety within a species, using recombination and gene shuffling, involving already existing dominant and recessive genes.
Mendel the first geneticist, proved in his experiments that there is a limit to how much change can occur.
Bacteria are the oldest living organisms, with the highest rate of mutation, but there exist no species of bacteria on its way to becoming something other than bacteria.
Dog breeding is a good example of variability built into DNA being limited as to how much change can occur.
After centuries of breeding dogs, there’s a tremendous amount of different dogs that now exist, of every conceivable size, and shape, but there are no dog breeds morphing into a new body plan - and they will never create anything other than another dog species.
Mutation experiments on drosophila fruit flies produced thousands of generations of radiated flies in an attempt to find one good mutation.
All they got were sickly flies, flies without wings, and flies with two sets of wings, but not one new trait or good mutation.
That’s because a mutation is a break in a DNA sequence/gene due to radiation, heat, or chemical, which Editase repairs, but sometimes something goes wrong with the repair.
The most common mutation is a stop codone, which causes a missing gene at that spot, resulting in something missing, such as a finger, for example, or a duplication of the gene, resulting in an extra finger, or a defective gene resulting in a malformed finger, for one example.
Hence all they got from the irradiated drosophila fly experiments, were deformed flies, flies missing wings, and flies with an extra set of wings, but nothing else.
Mutations are not a mechanism that can cause macro evolution, or write new DNA code, despite what’s in the high school and college textbooks, or National Geographic or Time magazine, or on PBS.
Shalom.