When changing pole top constructions, you need to make sure that you have set the correct number of conductors prior to updating the pole top construction.
1. Select the conductor set with the pole top construction you want to update.
2. In General settings, update the Num# cables
3. Go to the construction you want to update. e.g. you can use bulk pole top construction edit, or edit on one pole only etc
4. Select the pole top construction you want to change to. Again, note that you will only be able to change between constructions with the same number of conductors.