Lychee Slicer is providing by default a list of different resin brands. But you may want to use another brand that is not listed.
When creating a new resin, the editor will display the "default" brand. You can select the name "default" and rename it to a custom name of your choice.
Click on the "Add" button in the Printer editor:
Then click on the "Add New Custom Resin":
Then select the "Default" text:
And rename it to your custom brand, let's say "Lychee Slicer Resin":
You can also type a custom type of resin and color as well: