ehm… bind it to a variable?
click your text widget->inside details->click on bind->Create Binding->A binding function appears->
->create an FText variable->give it a default text(optional)->drag it into the function and connect the variable with the return pin
so now you can alter the text when you modify the FText variable.
OR make your TextWidget a “Variable” and access it as an object and then call “Set Text”.