Using following steps you can add your own custom logo in footer.
1. Step 1 : Hide the footer logo
Add this CSS code to location given:
wp admin panel -> Plugins->Editor->WPLMS Customizer Plugin -> Custom.css
OR
Wp Admin->Appearance->Customize->Custom CSS
Code:
#footerlogo{
display:none;
}
2. Step 2 : Upload the Logo in WP Media
3. Step 3 : Add the logo in the WPLMS Options panel -> Footer -> Copyright Section.
Refer below video on how to do this :