when I made a change with the brush, the gray slider to select the editing no longer appears. How to find this slider?
Please post a screen shot of what you are seeing.
Do you mean the gray circles that show where the brush edits were started from, IE the fist place you clicked to start the brush edits? If that is what you are looking for you have hidden them. Hit the H (lower case) key to hide or show (un-hide) them/it.
Ok thank you