Use the icon that looks like a landscape picture to attach full files. The Apple crash report will probably be the most helpful. You can find them in ~/Library/Logs/DiagnosticReports/ (where ~ refers to your Home directory, & some folders may be hidden by default).
Otherwise, a good place to look is at the preferences. Move the preferences folder (found in the Output folder) to the desktop, then restart X‑Plane and default preferences will be restored. If the default preferences do not fix your problem, you can simply replace them with the folder you moved to the desktop and restore your personalized settings.
The final common culprit is third party add ons, such as scenery and plugins. Try moving the Custom Scenery folder and plugins folder (found in the Resources folder) to the desktop, then restart X-Plane.