There is no way to "enable" dual channel. Dual channel memory operation happens when there are two DIMMs that are fully compatible with each other are installed in a motherboard that has dual channel support capability. If there is a DIMM installed in each channel, which for boards with only two DIMM slots generally means one DIMM in each slot, or in the correct slots on a motherboard with four DIMM slots, which is generally going to be the A2 and B2 slots if only two DIMM are used (Or at least matching DIMMs in those slots and then matching DIMMs in the remaining two DIMM slots if four DIMMs are used).
So without at least two memory modules installed, regardless of what type of motherboard it is, you can't have dual channel operation as there needs to be at least one DIMM installed in each memory channel slot. If your laptop has two DIMM slots, then you'll need to source another identical DIMM or at least one with specs that are as exactly the same as possible, and install that, and then it should automatically run in dual channel. In some cases you might have to reset the BIOS to get it to make the change but for laptops usually not, unlike many desktop boards.
In any case, dual channel is not a "setting" and cannot be "enabled" or "disabled". You either meet the criteria and it works, or it doesn't. If it doesn't, then you have to figure out why but if you have two DIMMs installed, it should.