This is a known issue in version 12.60, and there is a hotfix to resolve this issue.

Parameter cannot be set to ''same line as''
Document ID : KM03263663
Product - Version: Performance Center 12.60 ; LoadRunner 12.60 ;
OS :
Updated : 2018-Oct-04
Summary :
Cannot set parameter to ''same line as'' in parameters list settings when few parameters exist. It keeps defaulting to ''sequential''
Solution
1. Please find the following Hotfix (Fix99994.zip) uploaded to the caseand unzip the zipped folder. It contains a fix for each language including English

2. Take a backup of the originalparamui.dll from[LoadRunner Installation Folder]bin
a. Remove the backup file from this directory

3. Place the selected language paramui.dll file from the Fix99994 folder into [LoadRunner Installation Folder]bin

The paramui.dll file will need to be replaced on each instance of Standalone VuGen and PC Host only in your ALM-PC 12.60 environment.

* VuGen default file path: C:Program Files (x86)Micro FocusVirtual User Generatorbin
* PC Host default file path: C:Program Files (x86)Micro FocusLoadRunnerbin

I hope this helps