Annotations on one sequence can be transferred to other sequences in the alignment:
right-click the annotation | Copy Annotation to other Sequences
This will display a dialog listing all the sequences in the alignment. Next to each sequence is a checkbox which is used for selecting which sequences, the annotation should be copied to. Click Copy to copy the annotation.
If you wish to copy all annotations on the sequence, click the Copy All Annotations to other Sequences.
Copied/transferred annotations will contain the same qualifier text as the original. That is, the text is not updated. As an example, if the annotation contains 'translation' as qualifier text this translation will be copied to the new sequence and will thus reflect the translation of the original sequence, not the new sequence, which may differ.