Open the editor
On the Rules tab, tap the rule's card, or open its menu and tap Edit. The Edit Rule screen opens on Review Your Sync Rule. The row of tabs at the top scrolls sideways; tap a tab to open it. See The Rules tab.
When you are done, tap Save, or Cancel to leave without changes.
The rule type, the account and the cloud folder are fixed once the rule exists and have no tab, and so is the phone folder of a rule that syncs one folder. To change them, create a new rule.
Label Your Rule
The rule's name, icon and color, and whether its button appears on the photo preview. See Sync from the photo preview.
Selected Albums
Only for rules that sync albums. Add or remove albums; each album has its own subfolder in the cloud folder.
What to sync
Which files the rule includes. Not shown for Backup selected files or Quick Upload rules.

File types to sync offers Photos & videos only, Photos, videos, and sidecar metadata (XMP) and All files matching custom patterns. Syncing files other than photos and videos needs the All Files Access permission; without it only Photos & videos only is offered.

The tab also has Include hidden files and folders, and Include Filters and Exclude Filters for name patterns.
Additional
What the rule does when files change or are deleted. Only the settings that apply to the rule type are shown:
- Monitor sub-folders: include files in subfolders. Shown for rules that sync one folder.
- Verify file content when matching: when a file already exists on both sides, compare its content and not only its size. Storage services that cannot report file content show this option as unavailable.
- Delete in cloud when unmark: for rules that upload files you mark one by one.
- Delete in cloud when device file deleted and Update cloud files when modified on device: for backup and two-way rules.
- Re-upload to cloud if file was deleted there and Re-upload to cloud if file was modified there: for backup rules.
- Delete on device when cloud file deleted and Update device files when modified on cloud: for download and two-way rules.
- Re-download from cloud if file was deleted on device and Re-download from cloud if file was modified on device: for download rules.
- If file with the same name exists in destination: only for Quick Upload rules.

The screenshot is an example. It does not show the starting settings of any rule type.
To learn which of these start on for each rule type, see Choose a rule type and Keep cloud copies after deleting on your phone.
Media Compression
Keep smaller versions on the phone while the originals stay in the cloud. See Compress photos and videos.
Schedule
Choose Use global schedule or Custom schedule with its own interval. A custom schedule needs auto-sync to be on; if it is off, the app offers to turn it on.

Confirmation thresholds
Whether the rule uses the global limits for deleting and updating files or its own. See Confirmation thresholds.
Share with others
Create a sharing link for the cloud folder. Shown only for some rules and storage services. See Share a folder.
Media Compression, Schedule and Confirmation thresholds are not shown for Quick Upload rules.