Unlike Signs, you can edit Slates, Posters, and Boards over and over again.
We were able to edit signs since version 1.20.
MCPE-191090
Outdated Sign Loading Tip in Minecraft Education
Resolved
Invalid
0
Thank you for your report!
However, this issue is Invalid.
Unfortunately we are only able to track bugs with Minecraft Bedrock Edition here.
Please visit the Education Edition Community Hub for assistance and bug reporting options.