Fixed Pairs or Americano: which one to choose?

Short answer

Fixed Pairs is the team that stays together the whole tournament, and the ranking belongs to the team. Americano is a rotation: your partner changes every round and the ranking is individual.

In 30 seconds

People arrived as ready-made pairs and want to play together? Fixed Pairs.
People came on their own and want to play with everybody? Americano.
In Americano you don't choose a scoring type — the ranking is always by games won per player.

Where to choose

The choice lives in Home › Create new tournament › Step 2 — Format › Tournament type. There are two cards, and the app itself sums each one up:

Fixed Pairs — “Teams are formed at the start and kept for the whole tournament.”
Americano — “Each round partners rotate — everyone plays with everyone.”

Right below comes the size. In Fixed Pairs you choose Super 5, Super 6, Super 7 or Super 8 — and the number counts teams, so a Super 8 is 16 people. In Americano you choose 4, 8 or 12 players — here the number counts people. With 8 players that's 7 rounds and 14 matches.

Side by side

	Fixed Pairs	Americano
Partner	The same, from the first match to the last	Changes every round
Ranking	The team's	Individual, per player
Size	5 to 8 teams (10 to 16 people)	4, 8 or 12 players
Scoring	Your choice: Simple, Standard or Games	Always the games each player wins
Matches tab	One queue: Next match, Pending, Completed	Grouped by Round 1, Round 2…

In Fixed Pairs, the Scoring type appears in the same Step 2: Simple (1 point per win), Standard (a win is worth 3 points — it's the one pre-selected) or Games (every game won counts in the ranking).

What goes wrong here

Picked Americano and the Scoring type disappeared? In its place you get the notice “Individual ranking: each player adds up the games they win in their matches.” It's not a bug — in Americano that choice doesn't exist.
“Super 8” counts teams: that's 16 people on the court. In Americano the number counts players. It's the most common mix-up when inviting.
After Generate and start in Step 4, the format can't be changed anymore. Picked wrong? Delete the tournament from the Tournaments list and create another.
In Americano, the Step 5 invite shows a partner — that only holds for the first round. Tell the group the partner changes.

Why it works this way

In Americano, the rotation schedule guarantees each player partners with every other player exactly once and faces every other player exactly twice, playing every round. It's not a draw: the schedules are pre-built and verified, which is why they only exist for 4, 8 and 12 players — the ones for 6, 10 and 16 haven't been built yet. Fixed Pairs is round-robin, with the match queue arranged so nobody plays twice in a row.