The General section of the Settings screen has an 
FSRS algorithm row. It shows which set of scheduling parameters your account is currently using and opens a modal where you can edit them manually or have them optimized automatically from your review history.
For what FSRS is and why parameters matter in the first place, see Learning methodology. This article only covers the Settings-screen controls.
The status badge
The value shown next to FSRS algorithm in Settings is one of three states:
| Status | Meaning |
|---|---|
| Default | You're using FSRS's standard, unpersonalized parameters. |
| Custom | You've manually edited at least one parameter. |
| Optimized | Your parameters were generated by running optimization on your own review history. |
This badge reflects which parameter set is active. It does not reflect whether an optimization is currently running. If a background optimization is in progress, that only shows inside the modal, described below.
If you manually edit parameters back to the exact default values, the badge returns to Default even if it previously said Custom or Optimized.
Editing parameters manually
Tapping the status row opens a parameter editor showing all 21 FSRS parameters as a raw JSON array. This is an advanced option: most people never need to touch it.
- Edit the array directly and tap Save. The array must have exactly 21 numeric values.
- Load Default Values resets the field to FSRS's standard parameters.
Saving a value that differs from the defaults sets your status to Custom. This editor is available to every user; it isn't a Pro feature.
Warning
Manual editing is intended for advanced users. Incorrect parameters can affect how your reviews are scheduled.
Automatic optimization
Optimization analyzes your own review history and computes personalized parameters from it, aiming for more accurate scheduling than the defaults provide. It's a flangu Pro feature.
Readiness
The modal shows a readiness indicator with your review count out of 1,000. Optimization needs a meaningful amount of review history to produce reliable parameters, so the Optimize Parameters button stays disabled until you reach 1,000 reviews. Below that, the indicator moves from "More reviews needed" to "Almost there" to "Ready for optimization" as your count climbs.
The modal also shows when your parameters were last optimized: Never, Today, Yesterday, or a relative time further back.
Running it
Once you're ready, tap Optimize Parameters. flangu queues the job and hands control back to you immediately: the modal closes and a message confirms optimization has started. You don't need to keep the app open or stay on this screen. The modal's own note says it typically takes one to two minutes, though it can take longer depending on how many reviews you have.
Optimization does not report progress inside the modal. Its result reaches you two ways:
- The FSRS algorithm status updates to Optimized the next time your device syncs.
- A push notification confirms the outcome: success, failure, or (if something changed since you last checked and your review count no longer qualifies) that more reviews are needed.
If you tap Optimize Parameters again while one is already running, flangu tells you an optimization is already in progress rather than starting a second one.
If a run fails, the button changes to Retry Optimization and the modal shows the error message it received.