Your thumbnail is not showing — the six reasons
A thumbnail that does not appear is rarely a bug. It is nearly always one of six specific situations, and they are easy to tell apart once you know what to look for. Work down the list in this order — it is arranged from most common to least.
1. It saved, but the caches have not caught up
Start here, because it is the answer most of the time. After you save a new thumbnail, YouTube rebuilds it at every size and distributes it through caches that expire on their own schedules. The watch page often updates first and the home feed last.
How to tell: open the video in a private window on another device. If the new thumbnail is there, everything worked and you are looking at a cache. Give it a few hours.
2. You never pressed Save
In YouTube Studio, choosing the file does not apply it. The Save button at the top right of the video details page is what commits the change, and leaving the page without it silently discards your selection.
How to tell: reopen the video's details page. If the old image is in the thumbnail slot rather than yours, it never saved.
3. Your account is not verified
Custom thumbnails are a verified-account feature. On an unverified channel there is no upload button at all — only the three auto-generated stills YouTube pulled from the video.
How to tell: look for the upload option. If it is simply absent rather than failing, verify your phone number in account settings and it appears.
4. The file broke a limit
The three limits that actually bite: format — JPG or PNG only, so a WebP or an iPhone HEIC will not go in; size — 2 MB from the phone app, 50 MB from a desktop browser; and ratio — 16:9 for normal videos, 9:16 for Shorts.
How to tell: the upload fails with an error rather than succeeding quietly. Convert to JPG or PNG and re-export at 1920 x 1080 and it will pass.
5. It was rejected on policy grounds
Thumbnails are covered by the Community Guidelines the same way videos are. Nudity or sexually provocative imagery, hate speech, violence and dangerous content get the thumbnail removed, and repeat offences can cost you the custom thumbnail feature for thirty days.
How to tell: you receive a notification. This is not a silent failure — if you were not told, this is not your problem.
6. It is a vertical video with a 16:9 thumbnail
The one almost nobody knows. A vertical video with a 16:9 custom thumbnail gets replaced by an auto-generated 4:5 image on the home, explore and subscriptions surfaces. Your thumbnail still shows on the watch page, in watch history and on non-mobile platforms.
How to tell: your design appears when you open the video, but not in the feed. That exact split is the signature of this case, and the fix is to design for the shape you are actually publishing.
The check that saves you an hour
Before you change anything, do this once. Sign out of YouTube, or open a private window, and load the video's URL on a phone that is not yours if you have one to hand. What you see there is what a stranger sees, without your account, your history or your browser's cache in the way.
If the correct thumbnail is there, the problem is entirely local and there is nothing to do. If the wrong one is there too, then the change genuinely has not propagated yet, and the next useful action is to wait rather than to re-upload. Re-uploading the same image repeatedly does not speed anything up; it just resets the clock on the caches that were already halfway through expiring.
The one thing worth doing while you wait is checking the file itself against the limits in the section above, because if it was going to fail on format or size it would have failed loudly at upload, and a silent wrong-image problem is almost never a file problem.
What to do about link previews
A separate case that gets blamed on YouTube: you paste the video link into WhatsApp, Discord, Slack or X, and the preview card shows the old thumbnail. That card is not served by YouTube at all. Each of those platforms fetches the page once, builds its own preview, and stores it for days.
Some of them expose a way to refresh it. Others do not, and the preview simply ages out. Either way it is not a signal that anything is wrong with your video, and it is not worth changing your thumbnail again over.
The same applies to a video embedded on your own website. The embed pulls its poster image on a schedule of its own, and a hard reload of your page is often enough to update it.
If none of the six fit
Two remaining possibilities. The video may be a Short, where the thumbnail comes from a frame you select unless you upload a 9:16 image specifically. Or you may be looking at an embed or a link preview on another site, which caches independently of YouTube and can be days behind.
Beyond that, sign out and open the video in a private window. Almost everything that looks like a YouTube fault at this point is a local cache or an extension rewriting the page.
Quick answers
My thumbnail shows in Studio but not in search.
That is a cache, not a failure. Search and the home feed are served from different caches than the watch page and can be several hours behind.
Why does YouTube keep using an auto-generated frame?
Either your account is not verified, so the custom option does not exist, or the file was refused for format, size or ratio. Both are visible on the details page.
Does a Short have a thumbnail?
Yes. By default it uses a frame from the video, but you can upload a 9:16 image. A 16:9 thumbnail does not fit a Short.
Can I lose the ability to upload thumbnails?
Yes. Repeated Community Guidelines violations in thumbnails can remove the custom thumbnail feature from your channel for thirty days.