Over time new features come to Android and developers update their apps, because these features aren't in older versions of Android eventually the app becomes incompatible with old devices.
Considering the Tab 3 is 10 plus years old the app probably isn't compatible anymore.
The Tab 3 has 1Gb of RAM . As YT streams larger packs of data to your device, the space gets used up quickly.
People have found this solution to work, making the old Tab 3 at 2Gb of memory use. It's called virtual swap space.
Read this posted thread carefully first before just jumping to it quickly.
As we all know, for what ever reason, Samsung decided to release the Tab 3 model tablets with 1 GB of ram. I believe this system needs more ram but unfortunately we cannot upgrade the hardware. What we can do is create virtual memory or a "Swap file" that acts like ram to help our Tab 3's out with multitasking and other memory hogging tasks. Below are the steps to:
Additionally, this works for the Jelly Bean and KitKat OS on the Tab 3. I've not read the entire thread to see if other OpenSource ROMs can utilize this method, like LineageOS making your Tab 3 Android 7. Some feel it does work.