Using sed to replace string

Hello guys,
I'm working in a cellular company and i'm trying to do a script to run some commands automaticlly.
I'm using Solaris version :SunOS pk-ercuas4 5.10 in my work. I've a file that creates by script named test1.mos that that look like:

confb+
gsg+

lt all

$date = `date +%d%m%y_%H%M`

l+ /home/yesumim/LTE_INT/LTE8282_2546_2547/10_Const_$nodename_$date.log

$RbsType = readinput(pls input RbsType eg RBS6601,:)
$hubPosition = readinput(pls input hubPosition eg A7,:)
$Is_Stand_Alon = readinput(pls input Is_Stand_Alon y/n,:)
.
.
.
.
l-

confb-
gs-

in this test.mos file i want to edit in place the 3 following lines:

 $RbsType = readinput(pls input RbsType eg RBS6601,:)
 $hubPosition = readinput(pls input hubPosition eg A7,:)
 $Is_Stand_Alon = readinput(pls input Is_Stand_Alon y/n,:) 

i want to put instad 3 variables i'm asking from the user before and replace them with this 3 lines to look like:

$RbsType = ofer 
$hubPosition = Genadi
$Is_Stand_Alon = Ido 

The first two lines I succedded to replace but in the third row I have a problem because of the "" (underscore) i'm searching for a solution to overwrite a string even if the string including a "" (underscore);

can some1 help me with this?

Welcome to the forum.

Please show the code that partially works for you so we can discuss what's wrong.