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I was recently in precisely the same boat and I had a bunch on notes I'd created on the Note 8 that I wanted to access on the Note 3 and 10.1. Well, the good news is that you can import the Note 8's notes to the newer devices. The bad news is that the reverse is not true (AFAIK), but hopefully, Samsung is working on something to correct this, if they haven't by the time you read this. So, to get those Note 8's into the Note 3 and Note 10.1 make sure you're synching all the devices with your Samsung account. Then...
1. Open S Note on your Note 3/10.1
2. Click Recent Note in the upper left-hand corner.
3. Click the Menu button and slect Import-->Samsung Account
4. Select the Notes you wan tto import or choose the Select All option, then click Done
Your Note 3/10.1 will show "Importing" as it concentrates on the task but when it's done, Voila!
Someone mentioned there was a PlayStore available viewer for viewing Note 3/Note 10.1 notes on older devices. I'll have to hunt around for that.
I hope this helps.