If you want to set up your logo in Openmeetings header you can do the following:

1. Create your logo image as PNG 40px height
2. Replace /opt/om/webapps/openmeetings/css/images/logo.png with your logo file

Customize OpenMeetings mobile icons

This is available in OpenMeetings 6.2.0 and later

First: Create the mobile icons assets. This can be done via a script

See also: Github: pwa-asset-generator

1. Install the generation script: npm install --global pwa-asset-generator
2. Locate your logo.svg (svg as input recommended) and place into an empty folder
3. Generate images and HTML using: pwa-asset-generator logo.svg

Second: Copy icons to relevant dir

The command above will generate all assets, place (and replace all) those into $OM_HOME/webapps/openmeetings/images/icons

You may need to clear your mobile device browser cache to see icons refresh.