If you notice that one of your photos has an incorrect date, you can modify it right within Google Photos. You can do that for individual photos or for multiple photos. Following is the step by step process to change the date and time on a single as well as multiple photos:
One by one in Google photos:
- Go to photos.google.com
- Click on the picture/video you want to change the date of
- At the right-hand side at the top click on the "i" icon
- In the pane on the right, you can change the date.
In bulk in Google Photos
- Go to photos.google.com or photos.google.com/albums
- Select multiple photos
- Click on "More options" (three dots icon)
- Select "Edit date & time".