I believe you should parent all the UI elements under the BoxOpeningBackground Instance, and resize them. If this doesn’t fix the issue, double check that the offset position of the UI elements is 0.
Scale and position your UI with the properties only. If you have any plugins that automatically scale your UI, remove them. Edit the property Position and Scale manually through the properties window. Sometimes, it is necessary to adjust the AnchorPoint of the UI to correct some screen-size related positioning issues.
Depends. If you are using UIAspectRatioConstraint, you should definitely have 1 frame as a background UI, and the rest of the elements as the child of the background frame. Otherwise, it’s really up to you, but I’d definitely suggest having 1 frame as a background frame, and every other element to your UI stays in that frame, if the UI you are making consists of multiple UI elements, as it’d be more organized.