Welcome to the forums. Unfortunately you have told us nothing as to your project starting with the hardware. No idea what you are getting at with adjusting servo motor resistance? Did you mean servo motor rotation? Please explain, in detail all of your project, hardware and any software code you have.
Read the following:
How to get the best out of this forumWelcome to the Arduino forum! A guide explaining how to get the best out of this forum is available at the link below. Please read it: 
0 16.8k Nov '20
BEGINNERS and LEARNERS read this...If you’re new, or learning the Arduino ropes, it can be hard to get started. Along with many good tutorials here and elsewhere - there is a section where you may explore or present guides that might help others. Introd… read more 
1 41.0k Dec '19
Demonstration code for several things at the same timeNOTE for newcomers. The demo is entirely contained in this Post and Reply #1. There is no need to read further unless you are interested. ...added 25Sep2014 There have been a few occasions recently where newcomers seeme… read more
Thank You
Ron