GPX files are used to store information about overlays, such as marks, routes and track logs. The app is designed to permit the operating system to open GPX files with Memory-Map.
However, Android's file association has always been unreliable, and it doesn't always work the way you expect! It is very dependent on the device manufacturer, the app used to open the file, and the setup of every other app installed on the device. It also depends on the configuration of the device sending the data, or the web site that you download it from. The reason is that Android primarily uses the MIME-type instead of the file extension.
If, when you try to open a GPX file, it opens with the wrong app, or it gives you a choice of apps but not including Memory-Map, it is best to simply "save" the file. The app doing the saving or downloading with normally place it in the "Download" folder.
Next, check app version in Menu > Settings > Help/About. If you are using version 2.9.0 or later, you can use Menu > Overlays, Menu
> Load Saved Data to browse for and open the file.
If you are using version 2.8.2 or before, you have to use a file manager app to move the file from the "Download" folder into the "Memory-Map" subfolder inside the Download folder. Then in the Memory-Map app, tap the Menu button , Overlays. Then menu
, and "Load Saved Data". If the file has been placed in Download/Memory-Map folder, then it will show up in the list of files you can open.
Another approach is to experiment with using a different email client app, a different browser, or a different file manager app, or whatever you are using as the app from which you are opening the file.
If you want play around with system settings to try to get the GPX file to open directly in Memory-Map, go to the Settings app and tap on the App settings. Go to the details for the app that is wrongly opening the file, and tap "Clear Defaults". (The location of this button varies, you may have to drill down in the settings).
Another option is to go to the app settings, tap the menu button at top-right, and tap "Reset App Preferences". Or you can try Uninstalling the app that is wrongly opening the GPX file. As a last resort, try giving the device a factory reset, and install Memory-Map before you install other apps. The behavior on some devices may depend on the order in which other apps are installed.
This sometimes, but not always, fixes the problem.
If you are using email, or a cloud service in order to copy data from Memory-Map on one device to another device, we recommend using the Memory-Map cloud-sync service instead of sharing GPX files.