BOOX Note Air 4 C · Troubleshooting
Apps look grey, blurry or ghosted on the BOOX Note Air 4 C
Text looks washed out, faint traces of old pages linger, or colour looks muddy. On the Note Air 4 C this is the refresh and colour settings, not a fault.
Symptoms
- Text and menus look grey rather than crisp black.
- Faint images of previous pages stay on screen.
- Scrolling a list or web page leaves a smeared trail.
- Colour content looks dull, grainy or low-resolution.
- One app looks fine and another looks terrible.
Before you start
- This is a settings problem in almost every case, not a broken screen.
- Have five minutes to change settings per affected app.
- The colour layer always looks slightly muted — that is how Kaleido e-ink works, not a fault.
- A true screen fault shows as a permanent line or blotch that a full refresh never clears.
Which fix do you need?
What are you seeing?
- Everything looks grey, in every app The global refresh mode is set too fast
- One specific app looks bad, others are fine That app needs its own optimisation set
- Plain text looks soft and greyish Switch that app to black-and-white mode
- Old pages linger until a manual refresh Raise the full-refresh frequency
- A permanent line or blotch that never clears Likely a hardware fault
Most common cause
The global refresh mode is left on a fast setting, an app has no per-app optimisation set, or a plain-text app is left in colour mode so text is softer and greyer than it needs to be. Ghosting is a full-refresh frequency set too low.
Fixes
Fix 1 Fix the global refresh mode
The global mode is the default every app uses until you give it its own. If it is on a fast setting, the whole device looks grey and grainy.
- Swipe down from the top-right for the control centre and find the refresh mode selector.
- Set it to "HD" or "Regal". Do not leave it on "Fast", "Speed", "Ultrafast" or "A2".
- Tap the manual "full-screen refresh" button once to clear the current ghosting, then check text.
Fix 2 Optimise the specific app, and set colour per app
Per-app settings override the global mode. An app with none set falls back to defaults that often look wrong, and a text app left in colour mode looks softer than it should.
- Long-press the app on the Apps screen and choose "Optimise", or use the control-centre optimisation icon.
- Set its refresh mode — HD or Regal for text, Balanced or Fast for a browser or store.
- For a plain-text reader, set the app to black-and-white. Keep colour only for comics, magazines, maps and photos.
- If text is grey, turn on "enhance contrast" or "bleach whites" a little — not to the maximum.
- If the app's layout is tiny or huge on the big screen, adjust the DPI slider, then reopen the app.
- Turn on "animation filter" to stop page-curl and fade effects that smear.
Fix 3 Deal with ghosting and rule out a hardware fault
Ghosting is normal e-ink behaviour that a full refresh clears, and it is a little more visible through the colour filter. If a full refresh never clears a mark, it is not ghosting.
- In the affected app's optimisation panel, set "full refresh every N pages" to 1 for the cleanest result, or 3 to 5 as a compromise.
- For KOReader, do this inside KOReader (menu, gear, Screen) and turn BOOX's app-level full refresh off.
- Add a "refresh" shortcut to the Navigation Ball for a one-tap manual clear any time.
- If a line, band or blotch stays after a manual full refresh and a restart, that is a panel fault — contact BOOX support with a photo.
Undo / recovery
All of these are settings changes and are safe to undo. The optimisation panel has a "reset" for each app, and the control centre lets you set the global mode back. Nothing here touches your books, notebooks or apps.
Related guides
If everything looks grey, fix the global refresh mode first. If it is one app, that app needs its own optimisation set — and for plain text, switch it to black-and-white for a sharper page. Ghosting that clears on a manual full refresh is normal; a mark that never clears is a hardware issue.