You can change the pixel dimensions of a still image in the Elements Organizer 12. You are not going to change the resolution of a video.
Select the photos of interest in the Elements Organizer 12.
Go to File Menu/Export As New File(s)
The Export New Files will look like this
1. Select JPEG
2. Where it says Size and Quality, click Custom to get the Custom Size dialog. Insert the pixel dimensions that you want, for example 1920 x 1080 or 1280 x 720 ----
3. Browse to and set for a new folder, like the one that we are discussing in another thread where we are using the approach of getting your Time Lapse photos from the hard drive save location into one folder with just them, in contrast to trying to gather them in from the Elements Organizer.
Is this what you are seeking in this thread?