To change the status of an App's Offline Availability you must first be in the 'Configure' section and scroll down to the 'Offline Availability' Template. Once there you can toggle the switch:
Offline Availability sets the default operational setting for the App. This can still be overridden at a User Level via the 'Applications' App in Site Settings. To see how to access these click here.
Enabling Offline Availability means upon User log in, the App Definition and the Record data in the Application will be synced into the Browser, taking advantage of 'IndexedDB' technology. This allows Users to continue to access, add and edit Records when they lose an internet connection. Any additional or changed Records will be stored as pending changes in the browser and thus, patch the values in when an internet connection is restored.
Consequently, it will take longer to sync the App when logging into the platform as it needs to put the App Data into the browser. However, this does bring increased speed in navigation and accessing of data due as it can taken from the data in the browser, instead of waiting for a server response upon each data request.
Make sure to click the 'Save' button when making any changes in order for them to be added to the next app version. Once you have made all the changes you need to an application you are then ready to publish it to workspace.
Note: Workflow and the running of Expressions happen on the server which means that these will require an internet connection. Please read this article before making this change to see the differences between online and offline - Offline vs. Online Applications - A Look at Variances – Softools
Recommendation: If your App contains a high volume of Fields and/or the Record count is large (>10,000 Records,) then we advise testing the speed of synchronisation with this data volume in the App. A judgement would then be needed to assess if the length of synchronisation is worth the benefit of having the App available offline.