When inserting an arrow, bike symbol or other block, it comes in much too big. This can also happen when in KeySIGN with the Real text letter blocks.
Step 1 - Type UNITS and check the insertion units value. KeyLINES, KeySIGNALS, AutoSTRIPE and AeroSTRIPE will all observe this setting. If it is set to mm then symbols and line markings will be 1000x bigger, so change this to metres or other units as required.
Step 2 - Type -DWGUNITS (the minus is required at the start of the command name). This step is only needed for those machines that have Civil AutoCAD installed. This command can also affect plain AutoCAD if there is both Civil and AutoCAD installed on the same machine.
-DWGUNITS will ask a series of questions. The forth question "Scale objects from other drawings upon insert? [Yes/No] <Yes>:" is the important one. Please answer N or No to this question.
This setting is saved separately within each dwg, so it might be important to check the setting/value in any dwt or template drawing that your organisation uses.