A. 1. Go to the Zalando app and navigate to the category you are interested in. 2. Tap on the filter icon and look for the 'Brand' option. 3. Select your desired brands and apply the filter. 4. If this does not work, clear the app cache and restart the app.

B. 1. If filtering by brands is still not functioning, check for any app updates in the Google Play Store. 2. Update the app if a new version is available and try filtering again.