How to disable sequential numbering for a *specific* column in spreadsheet?

[TonyOne_Savage]

Would anyone be kind enough to help me solve disabling sequential numbering for specific columns in my spreadsheet? It's confidential information for work so I cannot share but essentially I want to drag a row down to automatically copy cells instead of filling series by default. So if I had something like TELC-18Z009, I want it to copy instead of TELC-18Z010, 11, etc. 

I know I can outright disable the drag + fill feature, but the sequential numbering feature is useful for other columns I have in the spreadsheet. I know that I can also hold ctrl as I drag and fill but I'd like to stop doing that and just straight up drag + fill instead. I've tried changing the column 'Number format' to 'Text' but that hasn't resulted in anything new. 

Also curious to hear if there's a way to change the default outcome after dragging + filling. For some of my columns the pop-out button is 'Copy Cells' and for others it is 'Fill Series'. If I can find a way to force it to default to one or the other that would also be a great workaround. 

Thank you!

[#2]

@TonyOne_Savage Press and hold the alt-key while dragging down. That should do it.

[#3]

One workaround is that you can use a formula
="TELC-18Z009"
That way if you drag, you just copy the formula and the value is always the same.

[#4]

For me it is the <ctrl> key that will stop the increment (force copy instead of sequence) as noted in the original post.
That said another alternative I found is you can click and drag using the right mouse button and it will bring up a contextual menu with multiple options (similar to pop-out button but automatically opens). Not sure that really solves the original complaint though.