Hello friends!

There are fixed lines on my sketch without any dimensions. I add a simple vertical line and then set a dimension of 38.65 to be 20. As a result the scale of all fixed lines diminishes.  How can I avoid this effect?

(Please note dimensions 55.72 and 28.83 were not actually put, only screenshotted; in case 55,72 is initially set, mistake of dimensioning fixed lines occurs).