Gfilui

Every time I boot up I have to switch my audio output device to my "Line Out" headphones because for some reason my microphone defaults as a speaker.

See this screenshot.

Here is a well explained tutorial to set a default audio input/output: Link

First: List the audio output devices using

pactl list short sinks

Example of the output:

pactl list short sources
0 alsa_output.pci-0000_02_00.1.hdmi-stereo.monitor module-alsa-card.c s16le 2ch 44100Hz SUSPENDED
1 alsa_input.usb-AVerMedia_Technologies__Inc._Live_Gamer_Portable_2_5202050100060-03.analog-stereo module-alsa-card.c 
2 alsa_output.usb-Blue_Microphones_Yeti_Stereo_Microphone_REV8-00.analog-stereo.monitor module-alsa-card.c s16le 2ch 44100Hz SUSPENDED
3 alsa_input.usb-Blue_Microphones_Yeti_Stereo_Microphone_REV8-00.analog-stereo module-alsa-card.c s16le 2ch 44100Hz RUNNING

Second: To set a default output device run the command

set-default-sink <'output device name'>

Example: pactl set-default-sink 'alsa_output.pci-0000_00_1f.3.analog-stereo'

Now, to make this work at every restart, follow this :

First, open the file /etc/pulse/default.pa using :

sudo gedit /etc/pulse/default.pa

Then scroll to the bottom of the file, where two lines starting with set- will be commented out.
Now, uncomment these lines and replace the words input and output with the number of the sink (for output) / source (for input) that you want to be the default.

Example:

### Make some devices default
set-default-sink 3
set-default-source 3

After doing this, save and exit. Then, delete the ~/.config/pulse directory by running sudo rm -r ~/.config/pulse, and then reboot the system. Once the system reboots, the appropriate devices should now be set as the defaults.