Microsoft has released cumulative update KB5102945 (Build 28120.2315) for Windows 11, version 26H1 for insiders on the Experimental channel.
- Accessibility. Improved responsiveness of the subtitle style — subtitles are now redrawn immediately when their style is changed. If subtitles are not currently displayed, a sample subtitle text is shown.
- Audio. Improved reliability of the built-in HD Audio driver.
Builds released to the Experimental channel (26H1) represent the latest platform changes at early stages of development and are not tied to any specific Windows release. Features and capabilities included in these builds may never ship in the final version, as Microsoft tries out different concepts and gathers feedback. Features may change, be removed, or replaced, and some of them may never become available outside the Windows Insider program. However, when these features are ready, they may appear in future Windows releases.
Many features on the Experimental channel (26H1) are rolled out using Controlled Feature Rollout technology. They first become available to a small group of insiders, and then their availability expands as feedback is received and analyzed to assess how they are perceived before becoming available to all participants on this channel.
Installation via Windows Update: Go to Settings > Windows Update and click Check for updates. A computer restart is required to complete the installation.
To update Windows 11, version 26H1 (Experimental) to build 28120.2315, you can also download update KB5102945 and install it manually using the links above.
| Feature / Change | Performance Increase or Decrease | Optimization | PC Speed | Gaming Optimization |
|---|---|---|---|---|
| Improved responsiveness of subtitle style redraw | ⚪ No measurable impact | 🟢 Low (instant UI redraw instead of delayed) | ⚪ No impact | ⚪ No impact |
| Improved reliability of built-in HD Audio driver | 🟢 Low (fewer audio dropouts, reduced CPU spikes from driver errors) | 🟢 Medium (more stable audio stack, fewer interruptions) | 🟢 Very Low (smoother audio processing reduces stutter) | 🟢 Low (more stable audio in games, fewer crackles/glitches) |
Find and Change Settings
| Setting | Where to find | How to change |
|---|---|---|
| Subtitle Style Responsiveness | Settings > Accessibility > Captions | Open Settings > Accessibility > Captions. Modify any subtitle style option such as font, size, color, or background. The preview sample updates immediately, and displayed subtitles redraw instantly to reflect your changes. |
| HD Audio Driver Reliability | Device Manager > Sound, video and game controllers | This improvement is applied automatically via Windows Update. To verify, open Device Manager, expand Sound, video and game controllers, right-click your audio device, select Properties, and check the Driver tab for the updated driver version. |
Official announcement on the Microsoft website.
The last 10 Windows updates:
| Update | Build | Version | Windows | Channel | Date |
|---|---|---|---|---|---|
| KB5121132 | 28120.2760 | 26H1 | Windows 11 | Experimental | 2026-08-21 |
| KB5124040 | 26220.9223 | 25H2 | Windows 11 | Beta | 2026-08-21 |
| KB5124042 | 26340.9233 | 26H2 | Windows 11 | Experimental | 2026-08-21 |
| KB5121106 | 28020.2731 | 26H1 | Windows 11 | Beta | 2026-08-17 |
| KB5121109 | 28120.2738 | 26H1 | Windows 11 | Experimental | 2026-08-17 |
| KB5124036 | 26220.9202 | 25H2 | Windows 11 | Beta | 2026-08-17 |
| KB5124038 | 26340.9212 | 26H2 | Windows 11 | Experimental | 2026-08-17 |
| KB5120996 | 28000.2796 | 26H1 | Windows 11 | Preview | 2026-08-14 |
| KB5120998 | 26200.9267 | 25H2 | Windows 11 | Preview | 2026-08-14 |
| KB5120240 | 22631.7517 | 23H2 | Windows 11 | Stable | 2026-08-11 |