We highly recommend to select the following two options in Extras > Options > Program options > Editors > LD/FBD editor:
Then you only need to enter variable identifiers in the empty name fields.
If the variable is not declared in the POU header, the variable will be created and added to the declaration.
The EV output does not need to be connected.
LD/FBD editor options
Shortcuts for programming in LD/FBD
Declaring new variables