When i import a world in minecraft, which a previously joined in multiplayer, how do I play as my multiplayer character rather than original creator?

A dedicated server is need.

Download dedicated server here: https://www.minecraft.net/en-us/download/server/bedrock/

Unzip and run bedrock_server.exe for a few seconds to generate the default world. Open server.properties and set online-mode=false ( https://www.minecraftforum.net/forums/support/minecraft-bedrock-support/2983414-authenticate-to-microsoft-services ).

Go into ./worlds/Bedrock level delete the content and past in you world.

Allow UWP apps to connect to localhost: Run PowerShell as admin and execute CheckNetIsolation LoopbackExempt -a -n="Microsoft.MinecraftUWP_8wekyb3d8bbwe" (https://pmmp.readthedocs.io/en/rtfd/faq/connecting/win10localhostcantconnect.html)

Open Minecraft Bedrock and add server ip 127.0.0.1 por 19132 (you can see the ports when you launch the server).