There might a few reasons why that happened:
1. Time zones have not been set consistently in your Account and your Calendar Settings page(s).
2. The generic date & time of your post got mixed up with the fine-tuned date & time of your post.
When you create a post in Post Builder:
In Step 1, you can define the generic date & time that will apply automatically to all the social media channels your post will be published for:
Then, in Step 4, you will be able to set a specific date & time for each social network you have selected:
The date defined in Step 1 is the generic date: similarly to how the generic copy & image / video work, that date will be applied to your post by default, unless you override it in the fine-tuning panel (Step 4) for a specific channel.
For simplicity, the generic date & time are displayed throughout the app, i.e. on your dashboard as well as in the list view, calendar view & post view. If you update the date & time of your post in the first panel of Post Builder (Step 1, see above), then that date & time will be displayed accordingly everywhere in Loomly. Unless you need to set a specific date for each channel, we recommend that you set the date & time of your post in Step 1 rather than in Step 4.