Raising Toilet Water Level

After I flush the toilet, the water level drains leaving very little water in the bowl. When I use the toilet, I constantly have to clean the toilet walls because the waste lands on the walls instead of water. It seems like this problem started when replacing the round ring under the toilet a few years ago, but not sure. What can I do to raise the amount of water in the bowl? Thanks

I have a 1.6 Toto that was installed when I bought the house 3 years ago.

Oops!

This should have been posted in toilet forum. Can a mod move it for me? Thanks