What Happens When You Clear an App's Cache?
A cache stores reusable temporary data, such as previously loaded images. Clearing it can free space or help with a loading problem; the app may need to download that material again.
The useful part
Clear cache and Clear storage/data are different actions. Clearing storage can remove local settings, sign-in state and unsynced files. Cache usually rebuilds, so repeated clearing is not a lasting cure for every problem.
Try this
On Android, open the app information page and look under Storage & cache. Start with Clear cache when troubleshooting. Before clearing storage, check that important local work is backed up. Menu names vary by phone.