In goalunited, the substitutions feature, along with other Half-time instructions, is currently being developed and tested from time to time in the game, either in League matches or in 1on1 matches during special events. Once fully developed, this will be available in all official competitions.
When enabled in matches, the substitutions can be made in the first half of the match, before half-time.
The Halftime instructions tab becomes active when the Substitutions are enabled.
You can replace a player by clicking the player in the formation that you want to replace and then clicking the player on the bench that you want to enter the field.
You can also move a player on the field by clicking the player, then clicking on a different position on the field.
You can also assign a job to a different player if you wish.
The complete formation has to be saved at least one hour before the start of the match.
At the moment, the only way to influence the match after this is to play half-time direction cards. Those can be played up to 50 minutes after the match has begun to react to an unsatisfactory first half.
When the Half-time instructions are disabled, the substitutions are automatically made only when a player gets injured during the match (it can happen in the first or second half)