You cannot. And, Premiere Elements 12 has the same YouTube limitations as 11.
You need to export your Timeline to a file saved to the computer hard drive, and then upload that file to YouTube at the YouTube web site.
At YouTube, you would need to explore the opportunities that it offers in the way of "extended times". It may require special accounts.
Without further details of your Premiere Elements project preset and the properties of your source media, I would generalize and suggest that you look at the follow choices for creating this file for upload to YouTube at the YouTube web site...
with Presets =
MP4 - H.264 1920 x 1080p30
YouTube Widescreen HD (changing the settings under the Advanced Button/Video Tab of the preset)
Please review. If you have any further questions on this, please do not hesitate to ask.
Yes. Thank you. Using the output that you suggested is what I have
done. I was merely asking about the default preset for "Online HD
Youtube" without having to do one separately as I am doing now. Thanks again.
Thanks for the follow up.
There are earlier versions of Premiere Elements where the Online/YouTube is 10 minutes. Adobe never patched that when it went to 15 minutes in the later versions.