Once units are placed on the battlefield, your troops are autonomous and cannot be controlled once they are deployed.
At the moment of deployment, each unit’s first target is highlighted with a red cross-hair. Different units will attack according to their abilities and preferred targets.
Check an individual unit’s information in the Barracks to find out what they are likely to go after first!
If you have any further questions about this or Battle Islands in general, please go to this page and fill out the game questionnaire!