the tiny ones you open up undercut, and seal.

HallerB , the more I think about it the more your solution sounds like the
right now. A little tiny strip of concrete paste would be useless against
those small cracks.

So I need to cut open the cracks a little more , ey .. do u recommend any
tool to make this go quicker? All I could think of off the top of my head
is a hammer and pick / screwdriver.