Hi @Anonymous :
Do you want to replace Ower in the table with the value in the FullName field? Something like:

to

If so,I've made a test for your reference:
1\Create a canvas and add Users and Your Data table as datasource:
2\Add a button and set it's OnSelect property to:
ClearCollect(TheSource,Homes.Home); /*Homes is my custom table*/ /*Home is the Guid column*/
ForAll(TheSource,
Patch(
Homes,
LookUp(Homes,Home = TheSource[@Home]),
{Owner:LookUp(Users,'Full Name' = LookUp(Homes,Home = TheSource[@Home]).Name)}
))
Best Regards,
Bof