Inserting grace notes

Yes, when you delete the eighth note, the grace notes are also deleted.

There are several ways to get what you want. This is perhaps the easiest:
1. Select the eighth note.
2. Press "6" then "." to have a dotted half.
3. Use arrow keys to get a C (natural or sharped? Either way, you can use "J" when necessary).
4. The G# quarter should be easy enough.

Exactly what problem do you have with inserting grace notes?
I can see that the grace notes in the first measure are correct, but symbols are used in the third measure.

By definition, grace notes are notes attached to other notes. So it is perfectly logical that if you delete the note the grace note is attached to, the grace note is deleted as well. Just as if there was a fingering marking on that note, or a lyric attached to it - it wouldn't make sense for them to stick around after deleting the note they are attached to.

Your problem seems to be that you entered a D eighth note that doesn't belong in the score, then compounded the problem by attaching grace notes to that D that shouldn't have been there in the first place. I think perhaps you were thinking the grace note icon was going to change the selected note into a grace note, but that is not what it does - it *inserts* a grace note in front of the selected note.

The method described in the previous response by Fyrult shows how to correct the error. But for the record, the correct way to have entered this in the first place would have been the following:

1) first enter the dotted half C (type "6 . C")
2) now enter the three grace notes (double click the grace note icon three times)
3) change the pitch of the grace notes using the arrow keys after entering them