You may experience picture and sound sync issues if the device you are casting to is using an older version of the Chromecast firmware. As of April 2024, you should have a version starting v1.56 installed, if you are not on this version please update your device.
You can find the latest version numbers and info on how to update your Chromecast device on the Google site: https://support.google.com/chromecast/answer/7124014?hl=en-gb
If you are using a version of Chromecast that is built into your TV you may need to contact that devices manufacturer for advice on how to check for the firmware version and how to update this if needed.
Note: Older Chromecast devices (gen 1) are no longer supported by Google, so will not be able to be updated.
Other things to try:
- If you cannot update your device then rebooting your Chromecast device and the device you are casting form may help in the short term.
- If you are up to date and are using an external speaker or soundbar then you may want to try switching to your TV's internal speakers to see if the issue is with syncing to the external device.