When you skip a word during spelling check by clicking Ignore All, or Correct All, the word is automatically inserted in the temporary exception dictionary, and you are not prompted any more for that word neither during the current spelling check,  nor in any spelling check you will perform later during the same work session.

The temporary dictionary is not saved on disk, but it is held in the memory, during entire work session.

If you want Fred4 to prompt you again for the skipped words, clear the temporary dictionary.

Note: it is not possible to clear separately words added by Ignore All and words added by Correct All.