Hello and welcome to Android Forums. Hopefully I can help you with your problem.
Sometimes devices just won't auto-connect for some reason.
Try this, go into your device's bluetooth settings, then tap settings and make sure you have any option to auto-connect is checked. Also, make sure the devices in question are being saved in the approved device list on your phone. If they aren't, that may be the reason they aren't auto-connecting.
There are also apps on Google Play that allow better bluetooth management. You may want to take a look at some of those.
Last but not least, there is a chance that somehow your bluetooth files have become corrupt. Usually doing a factory reset will fix that. Just keep in mind that you will lose all of your data using this option. Making a backup is highly suggested.
If your device isn't rooted, you may want to look into rooting it. By doing so, you will have better access to your phone files and it will also broaden the apps you have to chose from if you decide to use a bluetooth app to control that feature.
Quite a few people I know use those bluetooth control apps.
If you have any other questions regarding your device, I invite you to join Android Forums. We have many sections for specific devices which contain a wealth of information.
