System themes vs Icon packs
Some phone manufacturers (and ROM creators) offer system level icon theming (Samsung, Huawei etc). On the other hand you will find many Icon packs in the Play Store which let you customize your launcher.
Bubble Cloud Widgets can use either of these: you can control their effects in two places:
► Assign Icon packs to bubble clouds in the ⊕ Cloud configuration screen.
► Choose if the System themes are used or not in the Main Bubble Cloud settings app → Widget Preferences → Expert mode
Consider these four cases:
1) Enable the “Default app icon” if you want the original icons provided by the creators of each app (instead of the icon provided by the Samsung theme for example). These default icons look best in color circles. Bubble Cloud Widgets will match the color of the circle to the dominant color of the icon.
2) Disable the option to use the themed icons provided by Samsung or other system level theming. Especially if these themed icons are round I recommend removing the color circles (by setting their opacity to 0% in the Cloud configuration screen).
3) NOT RECOMMENDED: if both the system level theming and an icon pack is active, you will get a combination of the two, which rarely looks good.
4) When you use an icon pack from the Google Play Store, it is best to mark the option “Theme highest res default app icons”, this way the original app icons and not the system themed icons will be used for apps not included in the icon pack. If the icon pack has round icons, it is recommended to turn off the color circle (see #2)
Every time you adjust these settings, make sure to click on the option “Apply icon pack” in the Cloud configuration screen to generate the new bubbles.
(Thank you Joseph Rubin for the screenshots and your permission to use them for this tutorial)