All the choices that would normally be made when the spell comes into a potion have already been made as part of the process of creating the potion. This includes all target choices because the target of a potion is always a drinker. So, I suspect that when Potions says that "the drinker always controls the effect," it means that everything In progress The effect is always under control as the effect of the spell allows its caster to have.
The biggest example of this is the spells that include in their duration the note that they are firing, as the spell invisibility. A drinker of the typical Invisibility potion (Level 2 spell at level 3), for example, is automatically considered both the thrower and the target of a invisibility goes out, but the drinker can take a standard action to cancel the effect before his normal 3 min. expires because the drinker controls the invisibility effect.
To be clear, the effect of the typical potion to heal minor wounds is to heal the consumer of 1d8 + 1 damage. This decision has already been made by the creator of the potion, and there is no alternative decision of the creator of the potion can make. In addition, the consumer of the potion is not allowed to simply opt out of this healing when the potion to heal minor wounds is consumed. (That's why they work on unconscious people.) The consumer of a potion is automatically and irrevocably considered. both the spell in the pitcher of the potion and his target.
(However, even an unconscious creature can choose to make a save-deposit save against a potion to heal minor wounds as a caster can – if she wishes – make a saving throw by will against her heal minor wounds to spell! For example, a GM may inform an unconscious PC fed to a potion to heal minor wounds only this no more the PC is entitled to a will save against an effect or the PC may intentionally fail a saving throw by will against the effect, the GM does not tell the player the nature of the effect nor the reason why the save throw is needed because the PC is unconscious! Although it's – for a fantasy game anyway-realistic and strictly according to the rules, I suspect that these GMs are in the minority.)
To address the other possibilities mentioned in the question, one of the least powerful magic missile potion (First level spell at caster level 1) at the entrance The targets up to five creatures, two of which can not be separated more than 15 feet so that must be a single creature – the drinker of the potion – depending on how it works. There is no other decisions to be taken regarding the magic missile spell: its range is now known and its damage is now fixed, for example. A more powerful magic missile potion (The level 1 spell at level 9 of the caster) asks its creator but an additional decision: How many missiles? And this decision is fixed when the potion is created, and the drinker will be the target of all the spells are missiles. The drinker does not even have the opportunity to make a saving throw! (Needless to say, a magic missile potion is often just funny once.)
Likewise, a shocking catch potion at the entrance Target the creature or object hit and, again, the drinker of the potion is automatically the target of the potion spell, and there is no other decision to make, and again, no saving throw is allowed. The drinker of one shocking catch potion is simply dealt the damage of the potion of the spell. (Beware, disturbing mounds: when you try to heal members of your party who are not menacing mounds, do not confuse your shocking catch potions with your potions to heal minor wounds!)