No alarm or silent during certain times I have used 2 applications, one for alarm and one for setting silent times (so I can not hear my phone during working hours and night time) but experience issues with them not sounding/working. 

For years, with my HTC One, I had no problems. I have now upgraded to Huawei P8 and have noticed an issue. Neither 'work' (meaning, the alarm doesn't sound) over a period of time. This means, if I set an alarm for 5 minutes time, it works. It could quite possibly work next day, and even several days, but within some time, it stops. 

I've some IT experience and did some testing and have realised that, when using my HTC(s) in the past, if I see what apps are running, I can close them (to free up RAM/resource). Even if I closed the alarm app or the silent application, it would still run in the background (I assume, maybe it automatically restarted) and work.

I assume the issue I have is likely to be down to the design of the different 'flavour' of the OS, despite both being Lollipop. Maybe the HTC would allow the 2 apps to restart them selves but the P8 could prevent this for security reasons (is there a set this type of control per app?). Maybe the HTC didn't "close" the app in the way I thought it did!?

The only thing I've done to this phone is changed the launcher (it's not rooted). 

My question is, do I have to keep these type of applications running in the background, meaning when I close other running apps, I just need to be more vigilant with which I close? Or even better, is there a setting I can change so these things keep running even when I close them (as they did with my HTC(s)).
Since I also realised it happens with widgets, I worked out it's due to battery saving. 

P8 has option to allow apps to run even screen off (To find this, go to Settings -> Power saving -> Protected apps), and it appears this also means in background (so they continue to run even if they're closed)! 

It's fixed my email widget and my SMS/bandwidth measuring programs. 

It has fixed my alarm, but not my 'silent time' application, but the phone has this option built in. Despite that, I will test another application to see.