Happy to try and help when I can
You can change a DUPLICATE theme in one (or both) of two ways:
• change properties in the Default Style
• make a new Style - inevitably based on the Default (starts as a replica of it); and apply the new Style (with the modifications of settings which you’ve made) to pages as needed
In all cases there are (at least) two (main) ways that such changes can be made (to either Theme Default, or your created Style):
1 - In the Styles properties (Configure (left hand spanner/wrench, top left of main RW page > Master Style (4th setting down) ), and
2 - by applying custom CSS in those cases where a property which you want to change isn’t specifically listed in the Theme’s changeable settings
Let us know how you get on and good luck!