If you’d like to change the date your photos & videos were taken, you have two possibilities:
Open the photo or video and click on the (i) symbol at the bottom in order to be shown the photo’s/video’s information. Then click on the pencil next to the date and enter in the correct time the photo/video was taken.
If you would like to change the time multiple photos & videos were taken, select the ones you’d like to modify and click on “Edit capture time” in the blue navigation bar. You can then either “Shift capture time” or “Set single capture time”:
Shift capture time: the date and time of all selected photos & videos will be shifted (e.g. +7 hours).
Set single capture time: all selected photos & videos will be assigned the same date and time (e.g. 01.01.2019 20:00).
Please note: the capture time will then only be adjusted in myCloud and not in the file itself. The EXIF data won’t be overwritten.